JerryScript types

jerry_init_flag_t

Enum that contains the following elements:

  • JERRY_INIT_EMPTY - empty flag set
  • JERRY_INIT_SHOW_OPCODES - dump byte-code to log after parse
  • JERRY_INIT_SHOW_REGEXP_OPCODES - dump regexp byte-code to log after compilation
  • JERRY_INIT_MEM_STATS - dump memory statistics

jerry_type_t

Enum that contains JerryScript API value types:

  • JERRY_TYPE_NONE - no type information
  • JERRY_TYPE_UNDEFINED - undefined type
  • JERRY_TYPE_NULL - null type
  • JERRY_TYPE_BOOLEAN - boolean type
  • JERRY_TYPE_NUMBER - number type
  • JERRY_TYPE_STRING - string type
  • JERRY_TYPE_OBJECT - object type
  • JERRY_TYPE_FUNCTION - function type
  • JERRY_TYPE_EXCEPTION - exception/abort type
  • JERRY_TYPE_SYMBOL - symbol type
  • JERRY_TYPE_BIGINT - bigint type

New in version 2.0.

Changed in version 2.4: Added JERRY_TYPE_BIGINT value.

jerry_object_type_t

Enum that contains JerryScript object value types:

  • JERRY_OBJECT_TYPE_NONE - Non-object type
  • JERRY_OBJECT_TYPE_GENERIC - Generic JavaScript object without any internal property
  • JERRY_OBJECT_TYPE_MODULE_NAMESPACE - Module namespace object
  • JERRY_OBJECT_TYPE_ARRAY - Array object
  • JERRY_OBJECT_TYPE_PROXY - Proxy object
  • JERRY_OBJECT_TYPE_SCRIPT - Script object (see jerry_parse)
  • JERRY_OBJECT_TYPE_MODULE - Module object (see jerry_parse)
  • JERRY_OBJECT_TYPE_PROMISE - Promise object
  • JERRY_OBJECT_TYPE_DATAVIEW - Dataview object
  • JERRY_OBJECT_TYPE_FUNCTION - Function object (see jerry_function_type)
  • JERRY_OBJECT_TYPE_TYPEDARRAY - %TypedArray% object (see jerry_typedarray_type)
  • JERRY_OBJECT_TYPE_ITERATOR - Iterator object (see jerry_iterator_type)
  • JERRY_OBJECT_TYPE_CONTAINER - Container object (see jerry_container_type)
  • JERRY_OBJECT_TYPE_ERROR - Error object (see jerry_error_type)
  • JERRY_OBJECT_TYPE_ARRAYBUFFER - ArrayBuffer object

  • JERRY_OBJECT_TYPE_SHARED_ARRAYBUFFER - SharedArrayBuffer object

  • JERRY_OBJECT_TYPE_ARGUMENTS - Arguments object
  • JERRY_OBJECT_TYPE_BOOLEAN - Boolean object
  • JERRY_OBJECT_TYPE_DATE - Date object
  • JERRY_OBJECT_TYPE_NUMBER - Number object
  • JERRY_OBJECT_TYPE_REGEXP - RegExp object
  • JERRY_OBJECT_TYPE_STRING - String object
  • JERRY_OBJECT_TYPE_SYMBOL - Symbol object
  • JERRY_OBJECT_TYPE_GENERATOR - Generator object
  • JERRY_OBJECT_TYPE_BIGINT - BigInt object
  • JERRY_OBJECT_TYPE_WEAKREF - WeakRef object

New in version 2.4.

Changed in version [[NEXT_RELEASE]]: Added JERRY_OBJECT_TYPE_MODULE_NAMESPACE, JERRY_OBJECT_TYPE_PROMISE, JERRY_OBJECT_TYPE_DATAVIEW, JERRY_OBJECT_TYPE_ERROR, JERRY_OBJECT_TYPE_SHARED_ARRAYBUFFER, JERRY_OBJECT_TYPE_WEAKREF, JERRY_OBJECT_TYPE_SCRIPT, and JERRY_OBJECT_TYPE_MODULE values.

jerry_function_type_t

Enum that contains JerryScript function value types:

  • JERRY_FUNCTION_TYPE_NONE - Non-function type
  • JERRY_FUNCTION_TYPE_GENERIC - Generic JavaScript function
  • JERRY_FUNCTION_TYPE_ACCESSOR - Accessor function
  • JERRY_FUNCTION_TYPE_BOUND - Bound function
  • JERRY_FUNCTION_TYPE_ARROW - Arrow function
  • JERRY_FUNCTION_TYPE_GENERATOR - Generator function object

New in version 2.4.

jerry_iterator_type_t

Enum that contains JerryScript iterator value types:

  • JERRY_ITERATOR_TYPE_NONE - Non-iterator type
  • JERRY_ITERATOR_TYPE_ARRAY - Array iterator
  • JERRY_ITERATOR_TYPE_STRING - String iterator
  • JERRY_ITERATOR_TYPE_MAP - Map iterator
  • JERRY_ITERATOR_TYPE_SET - Set iterator

New in version 2.4.

jerry_proxy_custom_behavior_t

These option bits allow specializing Proxies with non-standard behaviour. These flags are recommended only for those trusted Proxies, whose handlers produce correct results.

  • JERRY_PROXY_SKIP_RESULT_VALIDATION - skip result validation for [[GetPrototypeOf]], [[SetPrototypeOf]], [[IsExtensible]], [[PreventExtensions]], [[GetOwnProperty]], [[DefineOwnProperty]], [[HasProperty]], [[Get]], [[Set]], [[Delete]] and [[OwnPropertyKeys]]

New in version [[NEXT_RELEASE]].

jerry_property_filter_t

Enum that contains JerryScript property filter options bits:

  • JERRY_PROPERTY_FILTER_ALL - List all property keys independently from key type or property value attributes (equivalent to Reflect.ownKeys call)
  • JERRY_PROPERTY_FILTER_TRAVERSE_PROTOTYPE_CHAIN - Include keys from the objects’ prototype chain as well
  • JERRY_PROPERTY_FILTER_EXCLUDE_NON_CONFIGURABLE - Exclude property key if the property is non-configurable
  • JERRY_PROPERTY_FILTER_EXCLUDE_NON_ENUMERABLE - Exclude property key if the property is non-enumerable
  • JERRY_PROPERTY_FILTER_EXCLUDE_NON_WRITABLE - Exclude property key if the property is non-writable
  • JERRY_PROPERTY_FILTER_EXCLUDE_STRINGS - Exclude property key if it is a string
  • JERRY_PROPERTY_FILTER_EXCLUDE_SYMBOLS - Exclude property key if it is a symbol
  • JERRY_PROPERTY_FILTER_EXCLUDE_INTEGER_INDICES - Exclude property key if it is an integer index
  • JERRY_PROPERTY_FILTER_INTEGER_INDICES_AS_NUMBER - By default integer index property keys are converted to string. Enabling this flags keeps integer index property keys as numbers

New in version 2.4.

Changed in version [[NEXT_RELEASE]]: The following values are modified due to a typo in their names (exlcude/exclude): JERRY_PROPERTY_FILTER_EXLCUDE_NON_CONFIGURABLE, JERRY_PROPERTY_FILTER_EXLCUDE_NON_ENUMERABLE, JERRY_PROPERTY_FILTER_EXLCUDE_NON_WRITABLE, JERRY_PROPERTY_FILTER_EXLCUDE_STRINGS, JERRY_PROPERTY_FILTER_EXLCUDE_SYMBOLS, JERRY_PROPERTY_FILTER_EXLCUDE_INTEGER_INDICES.

jerry_error_t

Possible types of an Error object:

  • JERRY_ERROR_COMMON - common error
  • JERRY_ERROR_EVAL - eval error
  • JERRY_ERROR_RANGE - range error
  • JERRY_ERROR_REFERENCE - reference error
  • JERRY_ERROR_SYNTAX - syntax error
  • JERRY_ERROR_TYPE - type error
  • JERRY_ERROR_URI - URI error

There is also a special value JERRY_ERROR_NONE which is not an error type this value can only be returned by the jerry_error_type.

Changed in version 2.0: The JERRY_ERROR_NONE was added to be used by the jerry_error_type method.

jerry_feature_t

Possible compile time enabled feature types:

  • JERRY_FEATURE_CPOINTER_32_BIT - 32 bit compressed pointers
  • JERRY_FEATURE_ERROR_MESSAGES - error messages
  • JERRY_FEATURE_JS_PARSER - js-parser
  • JERRY_FEATURE_HEAP_STATS - memory statistics
  • JERRY_FEATURE_PARSER_DUMP - parser byte-code dumps
  • JERRY_FEATURE_REGEXP_DUMP - regexp byte-code dumps
  • JERRY_FEATURE_SNAPSHOT_SAVE - saving snapshot files
  • JERRY_FEATURE_SNAPSHOT_EXEC - executing snapshot files
  • JERRY_FEATURE_DEBUGGER - debugging
  • JERRY_FEATURE_VM_EXEC_STOP - stopping ECMAScript execution
  • JERRY_FEATURE_VM_THROW - capturing ECMAScript throws
  • JERRY_FEATURE_JSON - JSON support
  • JERRY_FEATURE_PROMISE - promise support
  • JERRY_FEATURE_TYPEDARRAY - Typedarray support
  • JERRY_FEATURE_DATE - Date support
  • JERRY_FEATURE_REGEXP - RegExp support
  • JERRY_FEATURE_LINE_INFO - line info available
  • JERRY_FEATURE_LOGGING - logging
  • JERRY_FEATURE_SYMBOL - symbol support
  • JERRY_FEATURE_DATAVIEW - DataView support
  • JERRY_FEATURE_PROXY - Proxy support
  • JERRY_FEATURE_MAP - Map support
  • JERRY_FEATURE_SET - Set support
  • JERRY_FEATURE_WEAKMAP - WeakMap support
  • JERRY_FEATURE_WEAKSET - WeakSet support
  • JERRY_FEATURE_BIGINT - BigInt support
  • JERRY_FEATURE_REALM - realm support
  • JERRY_FEATURE_GLOBAL_THIS - GlobalThisValue support
  • JERRY_FEATURE_PROMISE_CALLBACK - Promise callback support
  • JERRY_FEATURE_MODULE - Module support
  • JERRY_FEATURE_WEAKREF - WeakRef support
  • JERRY_FEATURE_FUNCTION_TO_STRING - function toString support

New in version 2.0.

Changed in version 2.3: Added JERRY_FEATURE_WEAKMAP, JERRY_FEATURE_WEAKSET values.

Changed in version 2.4: Added JERRY_FEATURE_BIGINT, JERRY_FEATURE_REALM values.

Changed in version [[NEXT_RELEASE]]: Added JERRY_FEATURE_VM_THROW, JERRY_FEATURE_GLOBAL_THIS, JERRY_FEATURE_PROMISE_CALLBACK, and JERRY_FEATURE_MODULE, JERRY_FEATURE_WEAKREF, and JERRY_FEATURE_FUNCTION_TO_STRING values.

jerry_container_type_t

Container object types:

  • JERRY_CONTAINER_TYPE_INVALID - Invalid container
  • JERRY_CONTAINER_TYPE_MAP - Map type
  • JERRY_CONTAINER_TYPE_SET - Set type
  • JERRY_CONTAINER_TYPE_WEAKMAP - WeakMap type
  • JERRY_CONTAINER_TYPE_WEAKSET - WeakSet type

New in version 2.3.

jerry_well_known_symbol_t

Well-known symbols:

  • JERRY_SYMBOL_ASYNC_ITERATOR - @@asyncIterator well-known symbol
  • JERRY_SYMBOL_HAS_INSTANCE - @@hasInstance well-known symbol
  • JERRY_SYMBOL_IS_CONCAT_SPREADABLE - @@isConcatSpreadable well-known symbol
  • JERRY_SYMBOL_ITERATOR - @@iterator well-known symbol
  • JERRY_SYMBOL_MATCH - @@match well-known symbol
  • JERRY_SYMBOL_REPLACE - @@replace well-known symbol
  • JERRY_SYMBOL_SEARCH - @@search well-known symbol
  • JERRY_SYMBOL_SPECIES - @@species well-known symbol
  • JERRY_SYMBOL_SPLIT - @@split well-known symbol
  • JERRY_SYMBOL_TO_PRIMITIVE - @@toPrimitive well-known symbol
  • JERRY_SYMBOL_TO_STRING_TAG - @@toStringTag well-known symbol
  • JERRY_SYMBOL_UNSCOPABLES - @@unscopables well-known symbol
  • JERRY_SYMBOL_MATCH_ALL - @@matchAll well-known symbol

New in version 2.4.

jerry_regexp_flags_t

RegExp object optional flags:

  • JERRY_REGEXP_FLAG_GLOBAL - global match; find all matches rather than stopping after the first match
  • JERRY_REGEXP_FLAG_IGNORE_CASE - ignore case
  • JERRY_REGEXP_FLAG_MULTILINE - multiline; treat beginning and end characters (^ and $) as working over multiple lines (i.e., match the beginning or end of each line (delimited by \n or \r), not only the very beginning or end of the whole input string)
  • JERRY_REGEXP_FLAG_STICKY - The sticky flag indicates that it matches only from the index indicated by the lastIndex property
  • JERRY_REGEXP_FLAG_UNICODE - The unicode flag enables various Unicode-related features
  • JERRY_REGEXP_FLAG_DOTALL -The dotall flag indicates that the dot special character (“.”) should additionally match the following line terminator (“newline”) characters in a string;

New in version 2.0.

Changed in version 2.4: Added JERRY_REGEXP_FLAG_STICKY, JERRY_REGEXP_FLAG_UNICODE , JERRY_REGEXP_FLAG_DOTALL values.

jerry_parse_option_enable_feature_t

Option bits for jerry_parse_options_t.

  • JERRY_PARSE_NO_OPTS - No options passed
  • JERRY_PARSE_STRICT_MODE - Enable strict mode
  • JERRY_PARSE_MODULE - Parse source as an ECMAScript module
  • JERRY_PARSE_HAS_ARGUMENT_LIST - argument_list field is valid, this also means that function parsing will be done
  • JERRY_PARSE_HAS_SOURCE_NAME - source_name field is valid
  • JERRY_PARSE_HAS_START - start_line and start_column fields are valid
  • JERRY_PARSE_HAS_USER_VALUE - user_value field is valid

New in version [[NEXT_RELEASE]].

Using both JERRY_PARSE_MODULE and JERRY_PARSE_HAS_ARGUMENT_LIST is an invalid combination and will result in an exception during parsing.

See also

jerry_gc_mode_t

Set garbage collection operational mode

  • JERRY_GC_PRESSURE_LOW - free unused objects
  • JERRY_GC_PRESSURE_HIGH - free as much memory as possible

The difference between JERRY_GC_PRESSURE_LOW and JERRY_GC_PRESSURE_HIGH is that the former keeps memory allocated for performance improvements such as property hash tables for large objects. The latter frees all possible memory blocks but the performance may drop after the garbage collection.

New in version 2.0.

jerry_frame_type_t

List of backtrace frame types returned by jerry_frame_type.

  • JERRY_BACKTRACE_FRAME_JS - indicates that the frame is created for a JavaScript function/method

New in version [[NEXT_RELEASE]].

jerry_generate_snapshot_opts_t

Flags for jerry_generate_snapshot:

  • JERRY_SNAPSHOT_SAVE_STATIC - generate static snapshot (see below)

Generate static snapshots Snapshots contain literal pools, and these literal pools contain references to constant literals (strings, numbers, etc.). When a snapshot is executed, these literals are converted to jerry values and the literal pool entries are changed to their corresponding jerry value. To support this conversion, the literals and literal pools are copied into RAM even if the JERRY_SNAPSHOT_EXEC_COPY_DATA option is passed to jerry_exec_snapshot. This non-negligible memory consumption can be avoided by using static snapshots. The literals of these snapshots are limited to magic strings and 28 bit signed integers, so their constant pools do not need to be loaded into the memory. Hence these snapshots can be executed from ROM.

Important note: The jerry_exec_snapshot function rejects static snapshots unless the JERRY_SNAPSHOT_EXEC_ALLOW_STATIC option bit is set. The caller must also ensure that the same magic strings are set by jerry_register_magic_strings when the snapshot is generated and executed. Furthermore the JERRY_SNAPSHOT_EXEC_COPY_DATA option is not allowed.

New in version 2.0.

Changed in version [[NEXT_RELEASE]]: The JERRY_SNAPSHOT_SAVE_STRICT value is removed, JERRY_PARSE_STRICT_MODE should be used instead.

jerry_exec_snapshot_opts_t

Flags for jerry_exec_snapshot functions:

  • JERRY_SNAPSHOT_EXEC_COPY_DATA - copy snapshot data into memory (see below)
  • JERRY_SNAPSHOT_EXEC_ALLOW_STATIC - allow executing static snapshots
  • JERRY_SNAPSHOT_EXEC_LOAD_AS_FUNCTION - load snapshot as function instead of executing it
  • JERRY_SNAPSHOT_EXEC_HAS_SOURCE_NAME - source_name field is valid in jerry_exec_snapshot_option_values_t
  • JERRY_SNAPSHOT_EXEC_HAS_USER_VALUE - user_value field is valid in jerry_exec_snapshot_option_values_t

Changed in version [[NEXT_RELEASE]]: The JERRY_SNAPSHOT_EXEC_LOAD_AS_FUNCTION value is added, which replaces the jerry_load_function_snapshot function.

Copy snapshot data into memory

By default the snapshot buffer is expected to be present in memory until jerry_cleanup is called. For example static const buffers compiled into the application binary satisfy this requirement.

If the snapshot buffer is freed after jerry_exec_snapshot is called the JERRY_SNAPSHOT_EXEC_COPY_DATA must be passed to copy the necessary parts of the snapshot buffer into memory.

The JERRY_SNAPSHOT_EXEC_COPY_DATA option is not allowed for static snapshots.

New in version 2.0.

jerry_char_t

Summary

Jerry’s char value

Prototype

typedef uint8_t jerry_char_t;

jerry_size_t

Summary

Jerry’s size

Prototype

typedef uint32_t jerry_size_t;

jerry_length_t

Summary

Jerry’s length

Prototype

typedef uint32_t jerry_length_t;

jerry_value_t

Summary

A JerryScript value can be undefined, null, boolean, number, string, object, or an exception value. Exception values represent thrown exceptions during execution. Exception values cannot be passed as an argument to regular API function, only to those that work with exception values specifically.

Returned and created values by the API functions must be freed with jerry_value_free when they are no longer needed.

Prototype

typedef uint32_t jerry_value_t;

jerry_context_data_manager_t

Summary

Structure that defines how a context data item will be initialized and deinitialized. JerryScript zeroes out the memory for the item by default, and if the init_cb field is not NULL, it will be called with the pointer to the memory as an additional custom initializer. The deinit_cb (if non-NULL) is called during a call to jerry_cleanup () to run any custom deinitialization before the VM has been fully cleaned up. The finalize_cb (if non-NULL) is also called during a call to jerry_cleanup () to run any custom deinitialization after the VM has been fully cleaned up. If bytes_needed field is 0, no buffer is allocated for the manager, callback functions are called with NULL pointer.

Prototype

typedef struct
{
  /**
   * Callback responsible for initializing a context item, or NULL to zero out the memory. This is called lazily, the
   * first time jerry_context_data () is called with this manager.
   *
   * @param [in] data The buffer that JerryScript allocated for the manager. The buffer is zeroed out. The size is
   * determined by the bytes_needed field. The buffer is kept alive until jerry_cleanup () is called.
   */
  void (*init_cb) (void *data);

  /**
   * Callback responsible for deinitializing a context item, or NULL. This is called as part of jerry_cleanup (),
   * right *before* the VM has been cleaned up. This is a good place to release strong references to jerry_value_t's
   * that the manager may be holding.
   * Note: because the VM has not been fully cleaned up yet, jerry_object_native_info_t free_cb's can still get called
   * *after* all deinit_cb's have been run. See finalize_cb for a callback that is guaranteed to run *after* all
   * free_cb's have been run.
   *
   * @param [in] data The buffer that JerryScript allocated for the manager.
   */
  void (*deinit_cb) (void *data);

  /**
   * Callback responsible for finalizing a context item, or NULL. This is called as part of jerry_cleanup (),
   * right *after* the VM has been cleaned up and destroyed and jerry_... APIs cannot be called any more. At this point,
   * all values in the VM have been cleaned up. This is a good place to clean up native state that can only be cleaned
   * up at the very end when there are no more VM values around that may need to access that state.
   *
   * @param [in] data The buffer that JerryScript allocated for the manager. After returning from this callback,
   * the data pointer may no longer be used.
   */
  void (*finalize_cb) (void *data);

  /**
   * Number of bytes to allocate for this manager. This is the size of the buffer that JerryScript will allocate on
   * behalf of the manager. The pointer to this buffer is passed into init_cb, deinit_cb and finalize_cb. It is also
   * returned from the jerry_context_data () API.
   */
  size_t bytes_needed;
} jerry_context_data_manager_t;

New in version 2.0.

jerry_context_alloc_t

Summary

Function type for allocating buffer for JerryScript context.

Prototype

typedef void *(*jerry_context_alloc_t) (size_t size, void *cb_data_p);
  • size - allocation size
  • cb_data_p - pointer to user data

New in version 2.0.

jerry_context_t

Summary

An opaque declaration of the JerryScript context structure.

Prototype

typedef struct jerry_context_t jerry_context_t;

New in version 2.0.

jerry_container_op_t

Enum that contains the supported container operation types

  • JERRY_CONTAINER_OP_ADD - Set/WeakSet add operation
  • JERRY_CONTAINER_OP_GET - Map/WeakMap get operation
  • JERRY_CONTAINER_OP_SET - Map/WeakMap set operation
  • JERRY_CONTAINER_OP_HAS - Set/WeakSet/Map/WeakMap has operation
  • JERRY_CONTAINER_OP_DELETE - Set/WeakSet/Map/WeakMap delete operation
  • JERRY_CONTAINER_OP_SIZE - Set/WeakSet/Map/WeakMap size operation
  • JERRY_CONTAINER_OP_CLEAR - Set/Map clear operation

New in version [[NEXT_RELEASE]].

jerry_binary_op_t

Enum that contains the supported binary operation types

  • JERRY_BIN_OP_EQUAL - equal comparison (==)
  • JERRY_BIN_OP_STRICT_EQUAL - strict equal comparison (===)
  • JERRY_BIN_OP_LESS - less relation (<)
  • JERRY_BIN_OP_LESS_EQUAL - less or equal relation (<=)
  • JERRY_BIN_OP_GREATER - greater relation (>)
  • JERRY_BIN_OP_GREATER_EQUAL - greater or equal relation (>=)
  • JERRY_BIN_OP_INSTANCEOF - instanceof operation
  • JERRY_BIN_OP_ADD - addition operator (+)
  • JERRY_BIN_OP_SUB - subtraction operator (-)
  • JERRY_BIN_OP_MUL - multiplication operator (*)
  • JERRY_BIN_OP_DIV - division operator (/)
  • JERRY_BIN_OP_REM - remainder operator (%)

New in version 2.0.

See also

jerry_property_descriptor_flags_t

Enum that contains the flags of property descriptors.

  • JERRY_PROP_NO_OPTS - empty property descriptor
  • JERRY_PROP_IS_CONFIGURABLE - [[Configurable]]
  • JERRY_PROP_IS_ENUMERABLE - [[Enumerable]]
  • JERRY_PROP_IS_WRITABLE - [[Writable]]
  • JERRY_PROP_IS_CONFIGURABLE_DEFINED - Is [[Configurable]] defined?
  • JERRY_PROP_IS_ENUMERABLE_DEFINED - Is [[Enumerable]] defined?
  • JERRY_PROP_IS_WRITABLE_DEFINED - Is [[Writable]] defined?
  • JERRY_PROP_IS_VALUE_DEFINED - Is [[Value]] defined?
  • JERRY_PROP_IS_GET_DEFINED - Is [[Get]] defined?
  • JERRY_PROP_IS_SET_DEFINED - Is [[Set]] defined?
  • JERRY_PROP_SHOULD_THROW - Should throw in case of an exception, instead of returning with false

New in version [[NEXT_RELEASE]].

See also

jerry_parse_options_t

Summary

Various configuration options for parsing functions such as jerry_parse.

Prototype

typedef struct
{
  uint32_t options; /**< combination of jerry_parse_option_enable_feature_t values */
  jerry_value_t argument_list; /**< function argument list if JERRY_PARSE_HAS_ARGUMENT_LIST is set in options
                                *   Note: must be string value */
  jerry_value_t source_name; /**< source name string (usually a file name)
                              *   if JERRY_PARSE_HAS_SOURCE_NAME is set in options
                              *   Note: must be string value */
  uint32_t start_line; /**< start line of the source code if JERRY_PARSE_HAS_START is set in options */
  uint32_t start_column; /**< start column of the source code if JERRY_PARSE_HAS_START is set in options */
  jerry_value_t user_value; /**< user value assigned to all functions created by this script including eval
                             *   calls executed by the script if JERRY_PARSE_HAS_USER_VALUE is set in options */
} jerry_parse_options_t;

New in version [[NEXT_RELEASE]].

See also

jerry_property_descriptor_t

Summary

Description of ECMA property descriptor. This struct can be used for the jerry_object_define_own_prop method to configure how the property should be registered.

The naming scheme is similar to the JavaScript Object.defineProperty method.

Fields should be used in pairs. That is if the is_value_defined is set to true the value field should contain the value for the property.

Prototype

typedef struct
{
  uint16_t flags; /**< any combination of jerry_property_descriptor_flags_t bits */
  jerry_value_t value; /**< [[Value]] */
  jerry_value_t getter; /**< [[Get]] */
  jerry_value_t setter; /**< [[Set]] */
} jerry_property_descriptor_t;

Changed in version [[NEXT_RELEASE]]: The is_value_defined, is_get_defined, is_set_defined, is_writable_defined, is_writable, is_enumerable_defined, is_enumerable, is_configurable_defined, and is_configurable fields are replaced by the flags field.

See also

jerry_frame_location_t

Summary

Source code location data retrieved by jerry_frame_location.

Prototype

typedef struct
{
  jerry_value_t source_name; /**< source name */
  jerry_size_t line; /**< line index */
  jerry_size_t column; /**< column index */
} jerry_frame_location_t;

New in version [[NEXT_RELEASE]].

jerry_frame_t

Summary

Backtrace frame data passed to the jerry_backtrace_cb_t handler. This is an internal data structure which fields can be accessed by helper functions such as jerry_frame_location.

Prototype

/**
 * Internal data structure for jerry_frame_t definition.
 */
struct jerry_frame_internal_t;

/**
 * Backtrace frame data passed to the jerry_backtrace_cb_t handler.
 */
typedef struct jerry_frame_internal_t jerry_frame_t;

New in version [[NEXT_RELEASE]].

jerry_heap_stats_t

Summary

Description of JerryScript heap memory stats. It is for memory profiling.

Prototype

typedef struct
{
  size_t version /**< the version of the stats struct */
  size_t size; /**< heap total size */
  size_t allocated_bytes; /**< currently allocated bytes */
  size_t peak_allocated_bytes; /**< peak allocated bytes */
  size_t reserved[4]; /**< padding for future extensions */
} jerry_heap_stats_t;

New in version 2.0.

See also

jerry_call_info_t

Summary

Call related information passed to jerry_external_handler_t.

Prototype

typedef struct jerry_call_info_t
{
  jerry_value_t function; /**< invoked function object */
  jerry_value_t this_value; /**< this value passed to the function */
  jerry_value_t new_target; /**< current new target value, undefined for non-constructor calls */
} jerry_call_info_t;

New in version [[NEXT_RELEASE]]. Contents of this struct replaces the jerry_get_new_target function.

See also

jerry_external_handler_t

Summary

Type of an external function handler

Prototype

typedef jerry_value_t (*jerry_external_handler_t) (const jerry_call_info_t *call_info_p,
                                                   const jerry_value_t args_p[],
                                                   const jerry_length_t args_count);
  • call_info_p - pointer to a jerry_call_info_t structure which holds call related information.
  • args_p - the function arguments, array of JavaScript values.
  • args_count - the number of arguments.
  • return value

See also

jerry_value_free_callback_t

Summary

Native free callback of generic value types.

Note:

  • Referred values by this method must have at least 1 reference. (Correct API usage satisfies this condition)

Prototype

typedef void (*jerry_value_free_callback_t) (void *native_p);

New in version [[NEXT_RELEASE]].

See also

jerry_object_native_free_cb_t

Summary

Native free callback of an object. The callback receives both the memory pointer and the type information passed to jerry_object_set_native_ptr.

Note:

  • Referred values by this method must have at least 1 reference. (Correct API usage satisfies this condition)

Prototype

typedef void (*jerry_object_native_free_cb_t) (void *native_p, struct jerry_object_native_info_t *info_p);

New in version 2.0: Renamed from jerry_object_free_callback_t.

Changed in version 2.2: API calls are once again allowed. (See note)

Changed in version [[NEXT_RELEASE]]: info_p argument is added

See also

jerry_external_string_free_cb_t

Summary

Free callback for external strings. See jerry_string_external_on_free for more information.

Prototype

typedef void (*jerry_external_string_free_cb_t) (jerry_char_t *string_p,
                                                 jerry_size_t string_size,
                                                 void *user_p);
  • string_p - external string pointer
  • string_size - size of external string
  • user_p - pointer passed when the external string is created

New in version [[NEXT_RELEASE]].

See also

jerry_error_object_created_cb_t

Summary

Decorator callback for Error objects. This native callback is called every time when an Error object is created and the decorator can create or update any properties of the newly created Error object.

Note:

  • The callback function cannot be called recursively, so the Error objects created when the callback is running are not updated.

Prototype

typedef void (*jerry_error_object_created_cb_t) (const jerry_value_t error_object, void *user_p);

New in version 2.4.

See also

jerry_module_state_t

An enum representing the current status of a module

  • JERRY_MODULE_STATE_INVALID - Return value for jerry_module_state when its argument is not a module
  • JERRY_MODULE_STATE_UNLINKED - Module is currently unlinked
  • JERRY_MODULE_STATE_LINKING - Module is currently being linked
  • JERRY_MODULE_STATE_LINKED - Module has been linked (its dependencies has been resolved)
  • JERRY_MODULE_STATE_EVALUATING - Module is currently being evaluated
  • JERRY_MODULE_STATE_EVALUATED - Module has been evaluated (its source code has been executed)
  • JERRY_MODULE_STATE_ERROR - An exception has been encountered before the evaluated state is reached

New in version [[NEXT_RELEASE]].

jerry_module_resolve_cb_t

Summary

Callback which is called by jerry_module_link to get the referenced module.

Note:

  • If realms are enabled, the returned module should be created in the current realm (see: jerry_current_realm)

Prototype

typedef jerry_value_t (*jerry_module_resolve_cb_t) (const jerry_value_t specifier,
                                                    const jerry_value_t referrer,
                                                    void *user_p);
  • specifier - a module specifier string (usually used as a path to the module)
  • referrer - a module object which contains the specifier in its source code
  • user_p - pointer passed to jerry_module_link.
  • return value
    • a module object - if it can be resolved successfully
    • an exception - otherwise

New in version [[NEXT_RELEASE]].

See also

jerry_module_import_cb_t

Summary

Callback which is called when an import is resolved dynamically to get the referenced module.

Note:

  • If the function returns with a promise, the import call returns with this promise. The application should try to resolve the requested module later. If the module is evaluated successfully, the returned promise should be resolved with the namespace object of the module. Otherwise, the returned promise should be rejected with an exception.
  • If the function returns with a resolved module, a promise is created and resolved with the namespace object of the module. The import call returns with the resolved promise.
  • If the function returns with an exception, a promise is created and rejected with the returned exception. The import call returns with the rejected promise.
  • All other return values are considered invalid. In this case the import call returns with a rejected promise. The rejected promise has a fixed error message, it does not specify the reason of the fail.
  • If realms are enabled, the returned module should be created in the current realm (see: jerry_current_realm)

Prototype

typedef jerry_value_t (*jerry_module_import_cb_t) (const jerry_value_t specifier,
                                                   const jerry_value_t user_value,
                                                   void *user_p);
  • specifier - a module specifier string (usually used as a path to the module)
  • user_value - the user value assigned to the script (see jerry_parse_options_t)
  • user_p - pointer passed to jerry_module_on_import.
  • return value
    • promise or resolved module - if the operation is successful
    • an exception - otherwise

New in version [[NEXT_RELEASE]].

See also

jerry_module_state_changed_cb_t

Summary

Callback which is called after the module enters into linked, evaluated or error state.

Prototype

typedef void (*jerry_module_state_changed_cb_t) (jerry_module_state_t new_state,
                                                 const jerry_value_t module,
                                                 const jerry_value_t value,
                                                 void *user_p);
  • new_state - new state of the module.
  • module - a module whose state is changed
  • value - depends on the state: undefined for linked, module script result for evaluated, and exception value for error state.
  • user_p - pointer passed to jerry_module_on_state_changed.

New in version [[NEXT_RELEASE]].

See also

jerry_module_import_meta_cb_t

Summary

Callback which is called when an import.meta expression of a module is evaluated the first time. The object returned by import.meta is passed as the meta_object argument to the callback, and the callback can set the initial status of the object (e.g. add properties or set prototype).

Prototype

typedef void (*jerry_module_import_meta_cb_t) (const jerry_value_t module,
                                               const jerry_value_t meta_object,
                                               void *user_p);
  • module - module whose import.meta object is requested.
  • meta_object - import.meta object created for the module.
  • user_p - pointer passed to jerry_module_on_import_meta.

New in version [[NEXT_RELEASE]].

See also

jerry_native_module_evaluate_cb_t

Summary

Callback which is called by jerry_module_evaluate to evaluate the native module.

Note:

Prototype

typedef jerry_value_t (*jerry_native_module_evaluate_cb_t) (const jerry_value_t native_module);
  • native_module - a native module
  • return value
    • any non-exception value - if the module is evaluated successfully
    • an exception - otherwise

New in version [[NEXT_RELEASE]].

See also

jerry_backtrace_cb_t

Summary

Callback function which is called by jerry_backtrace_capture for each stack frame.

Prototype

typedef bool (*jerry_backtrace_cb_t) (jerry_frame_t *frame_p, void *user_p);
  • frame_p - pointer to jerry_frame_t data.
  • user_p - pointer passed to jerry_backtrace_capture.
  • return value
    • true, to continue capturing more frames
    • false, to end the stack capturing

New in version [[NEXT_RELEASE]].

See also

jerry_object_native_info_t

Summary

Type information for native pointers. Since each native pointer has a type information, multiple native pointers can be assigned to an object, and these can be updated or deleted independently.

The type information has a free callback, which is called when the object is freed by the garbage collector. If the callback is NULL, the application is not notified about the destruction of the object.

The buffer pointed by the native pointer can have a fixed number of jerry values, which refer to other values as long as the object is alive. The starting byte offset and the number of these values are specified by offset_of_references and number_of_references fields respectively. Before a buffer is attached to an object by jerry_object_set_native_ptr, the values must be initialized to undefined by jerry_native_ptr_init. When a buffer is no longer attached to any object, the jerry_native_ptr_free must be called to release the values. A single buffer can be attached to any number of living objects. When a buffer is currently attached to at least one object, the references can be updated by jerry_native_ptr_set. However, if the buffer is no longer attached to an object, the finalize function must be called even if the buffer is reattached to another object later. In this case, calling the init function after the finalization is optional, because the finalize function also initializes all values to undefined.

Prototype

typedef struct
{
  jerry_object_native_free_cb_t free_cb; /**< the free callback of the native pointer */
  uint16_t number_of_references; /**< the number of value references which are marked by the garbage collector */
  uint16_t offset_of_references; /**< byte offset indicating the start offset of value
                                  *   references in the user allocated buffer */
} jerry_object_native_info_t;

New in version 2.0.

Changed in version [[NEXT_RELEASE]]: Added number_of_references, and offset_of_references fields.

See also

jerry_object_property_foreach_cb_t

Summary

Function type used as a callback for the jerry_object_foreach method. A function with this type must return “true” to continue the iteration or “false” to finish the iteration on the object’s properties.

Prototype

typedef bool (*jerry_object_property_foreach_cb_t) (const jerry_value_t property_name,
                                                    const jerry_value_t property_value,
                                                    void *user_data_p);
  • property_name - a property name, this is not always a string.
  • property_value - the value for the given property.
  • user_data_p - optional user data pointer supplied via the (jerry_object_foreach)[#jerry_object_foreach] method.
  • return value
    • true, to continue the iteration
    • false, to stop the iteration

See also

jerry_foreach_live_object_cb_t

Summary

Function type used as a callback for the (jerry_foreach_live_object)[#jerry_foreach_live_object] method. A function with this type must return “true” to continue the iteration or “false” to finish the iteration on the object’s properties.

Prototype

typedef bool (*jerry_foreach_live_object_cb_t) (const jerry_value_t object,
                                                void *user_data_p);
  • object - the current JavaScript object in the for-each iteration.
  • user_data_p - optional user data pointer supplied via the (jerry_foreach_live_object)[#jerry_foreach_live_object] method.
  • return value
    • true, to continue the iteration
    • false, to stop the iteration

New in version 2.0.

See also

jerry_foreach_live_object_with_info_cb_t

Summary

Function type used as a callback for the (jerry_foreach_live_object_with_info)[#jerry_foreach_live_object_with_info] method. A function with this type must return “true” to continue the iteration or “false” to finish the iteration on the object’s properties.

Prototype

typedef bool (*jerry_foreach_live_object_with_info_cb_t) (const jerry_value_t object,
                                                          void *object_data_p,
                                                          void *user_data_p);
  • object - the current JavaScript object in the for-each iteration.
  • object_data_p - the current object’s native data pointer.
  • user_data_p - optional user data pointer supplied via the (jerry_foreach_live_object_with_info)[#jerry_foreach_live_object_with_info] method.
  • return value
    • true, to continue the iteration
    • false, to stop the iteration

New in version 2.0.

See also

jerry_halt_cb_t

Summary

Callback which is called periodically by the engine, and polls whether the ECMAScript execution should be stopped. If the callback returns with an undefined value the ECMAScript execution continues. Otherwise the result is thrown by the engine as an exception, and execution returns to the caller. The callback function might be called again even if it threw an exception. In this case the function must throw the same exception again.

Prototype

typedef jerry_value_t (*jerry_halt_cb_t) (void *user_p);

New in version 2.0.

See also

jerry_throw_cb_t

Summary

Callback which is called when a value is thrown in an ECMAScript code. The callback should not change the exception_value. The callback is not called again until the value is caught.

Note:

  • The engine considers exceptions thrown by external functions as never caught. The application can maintain a status flag to ignore the next call of the callback if necessary. See: jerry_function_external

Prototype

typedef void (*jerry_throw_cb_t) (const jerry_value_t error_value, void *user_p);

New in [[NEXT_RELEASE]].

See also

jerry_promise_state_t

Enum which describes the state of a Promise.

Possible values:

  • JERRY_PROMISE_STATE_NONE - Invalid/Unknown state (possibly called on a non-promise object).
  • JERRY_PROMISE_STATE_PENDING - Promise is in “Pending” state.
  • JERRY_PROMISE_STATE_FULFILLED - Promise is in “Fulfilled” state.
  • JERRY_PROMISE_STATE_REJECTED - Promise is in “Rejected” state.

New in version 2.2.

See also

jerry_promise_event_type_t

Event types for jerry_promise_event_cb_t callback function. The description of the object and value arguments are provided for each type.

Possible values:

  • JERRY_PROMISE_EVENT_CREATE - A new Promise object is created.
    • object - the new Promise object
    • value - parent Promise for then chains, undefined otherwise.
  • JERRY_PROMISE_EVENT_RESOLVE - Called when a Promise is about to be resolved.
    • object - the Promise object
    • value - value for resolving.
  • JERRY_PROMISE_EVENT_REJECT - Called when a Promise is about to be rejected.
    • object - the Promise object
    • value - value for rejecting.
  • JERRY_PROMISE_EVENT_RESOLVE_FULFILLED - Called when a resolve is called on a fulfilled Promise.
    • object - the Promise object
    • value - value for resolving
  • JERRY_PROMISE_EVENT_REJECT_FULFILLED - Called when a reject is called on a fulfilled Promise.
    • object - the Promise object
    • value - value for rejecting
  • JERRY_PROMISE_EVENT_REJECT_WITHOUT_HANDLER - Called when a Promise is rejected without a handler.
    • object - the Promise object
    • value - value for rejecting
  • JERRY_PROMISE_EVENT_CATCH_HANDLER_ADDED - Called when a catch handler is added to a rejected Promise which did not have a catch handler before.
    • object - the Promise object
    • value - undefined
  • JERRY_PROMISE_EVENT_BEFORE_REACTION_JOB - Called before executing a Promise reaction job.
    • object - the Promise object
    • value - undefined
  • JERRY_PROMISE_EVENT_AFTER_REACTION_JOB - Called after a Promise reaction job is completed.
    • object - the Promise object
    • value - undefined
  • JERRY_PROMISE_EVENT_ASYNC_AWAIT - Called when an async function awaits the result of a Promise object.
    • object - internal object representing the execution status
    • value - the Promise object
  • JERRY_PROMISE_EVENT_ASYNC_BEFORE_RESOLVE - Called when an async function is continued with resolve.
    • object - internal object representing the execution status
    • value - value for resolving
  • JERRY_PROMISE_EVENT_ASYNC_BEFORE_REJECT - Called when an async function is continued with reject.
    • object - internal object representing the execution status
    • value - value for rejecting
  • JERRY_PROMISE_EVENT_ASYNC_AFTER_RESOLVE - Called when an async function resolve is completed.
    • object - internal object representing the execution status
    • value - value for resolving
  • JERRY_PROMISE_EVENT_ASYNC_AFTER_REJECT - Called when an async function reject is completed.
    • object - internal object representing the execution status
    • value - value for rejecting

New in version [[NEXT_RELEASE]].

See also

jerry_promise_event_filter_t

Filter types for jerry_promise_on_event callback function. The callback is only called for those events which are enabled by the filters. The events are described in jerry_promise_event_type_t.

Possible values:

  • JERRY_PROMISE_EVENT_FILTER_DISABLE - Disable reporting of all events.
  • JERRY_PROMISE_EVENT_FILTER_CREATE - Enables the following event:
    • JERRY_PROMISE_EVENT_CREATE
  • JERRY_PROMISE_EVENT_FILTER_RESOLVE - Enables the following event:
    • JERRY_PROMISE_EVENT_RESOLVE
  • JERRY_PROMISE_EVENT_FILTER_REJECT - Enables the following event:
    • JERRY_PROMISE_EVENT_REJECT
  • JERRY_PROMISE_EVENT_FILTER_ERROR - Enables the following events:
    • JERRY_PROMISE_EVENT_RESOLVE_FULFILLED
    • JERRY_PROMISE_EVENT_REJECT_FULFILLED
    • JERRY_PROMISE_EVENT_REJECT_WITHOUT_HANDLER
    • JERRY_PROMISE_EVENT_CATCH_HANDLER_ADDED
  • JERRY_PROMISE_EVENT_FILTER_REACTION_JOB - Enables the following events:
    • JERRY_PROMISE_EVENT_BEFORE_REACTION_JOB
    • JERRY_PROMISE_EVENT_AFTER_REACTION_JOB
  • JERRY_PROMISE_EVENT_FILTER_ASYNC_MAIN - Enables the following events:
    • JERRY_PROMISE_EVENT_ASYNC_AWAIT
  • JERRY_PROMISE_EVENT_FILTER_ASYNC_REACTION_JOB - Enables the following events:
    • JERRY_PROMISE_EVENT_ASYNC_BEFORE_RESOLVE
    • JERRY_PROMISE_EVENT_ASYNC_BEFORE_REJECT
    • JERRY_PROMISE_EVENT_ASYNC_AFTER_RESOLVE
    • JERRY_PROMISE_EVENT_ASYNC_AFTER_REJECT

New in version [[NEXT_RELEASE]].

See also

jerry_promise_event_cb_t

Summary

Notification callback for tracking Promise and async function operations. The arguments passed to the callback depends on the event_type which is detailed in the description of jerry_promise_event_type_t.

Prototype

typedef void (*jerry_promise_event_cb_t) (jerry_promise_event_type_t event_type,
                                          const jerry_value_t object, const jerry_value_t value,
                                          void *user_p);
  • event_type - type of the event notification.
  • object - object corresponding to the event.
  • value - optional value argument.
  • user_data_p - optional user data pointer supplied via the (jerry_promise_on_event)[#jerry_promise_on_event] method.

New in version [[NEXT_RELEASE]].

See also

jerry_typedarray_type_t

Enum which describes the TypedArray types. Possible values:

  • JERRY_TYPEDARRAY_UINT8 - represents the Uint8Array TypedArray
  • JERRY_TYPEDARRAY_UINT8CLAMPED - represents the Uint8ClampedArray TypedArray
  • JERRY_TYPEDARRAY_INT8 - represents the Int8Array TypedArray
  • JERRY_TYPEDARRAY_UINT16 - represents the Uint16Array TypedArray
  • JERRY_TYPEDARRAY_INT16 - represents the Int16Array TypedArray
  • JERRY_TYPEDARRAY_UINT32 - represents the Uint32Array TypedArray
  • JERRY_TYPEDARRAY_INT32 - represents the Int32Array TypedArray
  • JERRY_TYPEDARRAY_FLOAT32 - represents the Float32Array TypedArray
  • JERRY_TYPEDARRAY_FLOAT64 - represents the Float64Array TypedArray
  • JERRY_TYPEDARRAY_BIGINT64 - represents the BigInt64Array TypedArray
  • JERRY_TYPEDARRAY_BIGUINT64 - represents the BigUint64Array TypedArray
  • JERRY_TYPEDARRAY_INVALID - represents an invalid TypedArray

API functions can return the JERRY_TYPEDARRAY_INVALID value if the TypedArray support is not in the engine.

New in version 2.0.

Changed in version 2.4: Added JERRY_TYPEDARRAY_BIGINT64, JERRY_TYPEDARRAY_BIGUINT64 values.

See also

jerry_exec_snapshot_option_values_t

Summary

Various configuration options for jerry_exec_snapshot

Prototype

typedef struct
{
  jerry_value_t source_name; /**< source name string (usually a file name)
                              *   if JERRY_SNAPSHOT_EXEC_HAS_SOURCE_NAME is set in exec_snapshot_opts
                              *   Note: non-string values are ignored */
  jerry_value_t user_value; /**< user value assigned to all functions created by this script including
                             *   eval calls executed by the script if JERRY_SNAPSHOT_EXEC_HAS_USER_VALUE
                             *   is set in exec_snapshot_opts */
} jerry_exec_snapshot_option_values_t;

New in version [[NEXT_RELEASE]].

See also

jerry_source_info_enabled_fields_t

Enum which describes the enabled fields of jerry_source_info_t. Possible values:

  • JERRY_SOURCE_INFO_HAS_SOURCE_CODE - source_code field is valid
  • JERRY_SOURCE_INFO_HAS_FUNCTION_ARGUMENTS - function_arguments field is valid
  • JERRY_SOURCE_INFO_HAS_SOURCE_RANGE - both source_range_start and source_range_length fields are valid

New in version [[NEXT_RELEASE]].

See also

jerry_source_info_t

Summary

Source related information of a script/module/function.

Prototype

typedef struct
{
  uint32_t enabled_fields; /**< combination of jerry_source_info_enabled_fields_t values */
  jerry_value_t source_code; /**< script source code or function body */
  jerry_value_t function_arguments; /**< function arguments */
  uint32_t source_range_start; /**< start position of the function in the source code */
  uint32_t source_range_length; /**< source length of the function in the source code */
} jerry_source_info_t;

New in version [[NEXT_RELEASE]].

See also

jerry_arraybuffer_type_t

Summary

Enum that contains the JerryScript type of an array buffer:

  • JERRY_ARRAYBUFFER_TYPE_ARRAYBUFFER - the object is an array buffer object
  • JERRY_ARRAYBUFFER_TYPE_SHARED_ARRAYBUFFER - the object is a shared array buffer object

New in version [[NEXT_RELEASE]].

See also

jerry_arraybuffer_allocate_cb_t

Summary

Callback for allocating the backing store of array buffer or shared array buffer objects.

Note:

Prototype

typedef uint8_t *(*jerry_arraybuffer_allocate_cb_t) (jerry_arraybuffer_type_t buffer_type,
                                                     uint32_t buffer_size,
                                                     void **arraybuffer_user_p,
                                                     void *user_p);
  • buffer_type - type of the array buffer object, see: jerry_arraybuffer_type_t.
  • buffer_size - size of the requested buffer.
  • arraybuffer_user_p - [in/out] user pointer assigned to the array buffer or shared array buffer object.
  • user_p - user pointer passed to jerry_arraybuffer_allocator
  • return value
    • Pointer to the buffer, if the allocation is successful, NULL otherwise.

New in version [[NEXT_RELEASE]].

See also

jerry_arraybuffer_free_cb_t

Summary

Callback for freeing the backing store of array buffer or shared array buffer objects.

Note:

Prototype

typedef void (*jerry_arraybuffer_free_cb_t) (jerry_arraybuffer_type_t buffer_type,
                                             uint8_t *buffer_p,
                                             uint32_t buffer_size,
                                             void *arraybuffer_user_p,
                                             void *user_p);
  • buffer_type - type of the array buffer object, see: jerry_arraybuffer_type_t.
  • buffer_p - pointer to the allocated buffer.
  • buffer_size - size of the allocated buffer.
  • arraybuffer_user_p - [in/out] user pointer assigned to the array buffer or shared array buffer object.
  • user_p - user pointer passed to jerry_arraybuffer_allocator

New in version [[NEXT_RELEASE]].

See also

General engine functions

jerry_init

Summary

Initializes the JerryScript engine, making it possible to run JavaScript code and perform operations on JavaScript values. This is required for almost all API functions.

Prototype

void
jerry_init (jerry_init_flag_t flags)

flags - combination of various engine configuration flags jerry_init_flag_t.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_SHOW_OPCODES | JERRY_INIT_SHOW_REGEXP_OPCODES);

  // ...

  jerry_cleanup ();
  return 0;
}

See also

jerry_cleanup

Summary

Finish JavaScript engine execution, freeing memory and JavaScript values.

Note: JavaScript values, received from engine, will be inaccessible after the cleanup.

Prototype

void
jerry_cleanup (void);

See also

jerry_context_data

Summary

Retrieve a pointer to the item stored within the current context by the given manager.

Note: Since internally the pointer to a manager’s context data item is linked to the next such pointer in a linked list, it is inadvisable to invoke too many different managers, because doing so will increase the time it takes to retrieve a manager’s context data item, degrading performance. For example, try to keep the number of managers below five.

Prototype

void *
jerry_context_data (const jerry_context_data_manager *manager_p);
  • manager_p: the manager of this context data item.
  • return value: the item created by manager_p when jerry_context_data () was first called, or a new item created by manager_p, which will be stored for future identical calls to jerry_context_data (), and which will be deinitialized using the deinit_cb callback provided by manager_p when the context will be destroyed.

New in version 2.0.

Example

#include "jerryscript.h"

typedef struct
{
  int my_data1;
  double my_data2;
  char *my_data3;
} my_context_data_t;

/* Define how context items will be initialized. */
static void
my_context_data_new (void *user_data_p)
{
  my_context_data_t *my_data_p = (my_context_data_t *) user_data_p;

  /*
   * Initialize my_data_p. JerryScript will store it on the current context and return it whenever
   * jerry_context_data () is called with a pointer to my_manager as defined below.
   */
}

/* Define how context items will be deinitialized */
static void
my_context_data_free (void *user_data_p)
{
  my_context_data_t *my_data_p = ((my_context_data_t *) user_data_p);

  /* Perform any necessary cleanup on my_data. JerryScript will free the pointer after this function completes. */
}

/* Wrap the creation and destruction functions into a manager */
static const jerry_context_data_manager_t my_manager =
{
  .init_cb = my_context_data_new,
  .deinit_cb = my_context_data_free,
  .bytes_needed = sizeof (my_context_data_t)
};

/*
 * Then, in some function in your code, you can retrieve an item of type my_context_data_t from the currently active
 * context such that JerryScript will create and store such an item if one was not previously created
 */
static void
someplace_in_the_code (void)
{
  my_context_data_t *my_data = (my_context_data_t *) jerry_context_data (&my_manager);
  /* Perform useful things using the data found in my_data */
}

jerry_register_magic_strings

Summary

Registers an external magic string array.

Notes:

  • The strings in the array must be sorted by size at first, then lexicographically.
  • The maximum number of external magic strings is limited to 2147483648 (UINT32_MAX / 2). If there are more than 2147483648 external magic strings the extra is cropped.

Prototype

void
jerry_register_magic_strings (const jerry_char_t * const *ex_str_items_p,
                              uint32_t count,
                              const jerry_length_t *str_lengths_p);
  • ex_str_items_p - character arrays, representing external magic strings’ contents
  • count - number of elements in ext_str_items_p array
  • str_lengths_p - array of lengths for each magic string

Changed in version 2.0: The first function argument type was changed.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  // must be static, because 'jerry_register_magic_strings' does not copy
  // the items must be sorted by size at first, then lexicographically
  static const jerry_char_t * const magic_string_items[] = {
                                                             (const jerry_char_t *) "magicstring1",
                                                             (const jerry_char_t *) "magicstring2",
                                                             (const jerry_char_t *) "magicstring3"
                                                           };
  uint32_t num_magic_string_items = (uint32_t) (sizeof (magic_string_items) / sizeof (jerry_char_t *));

  // must be static, because 'jerry_register_magic_strings' does not copy
  static const jerry_length_t magic_string_lengths[] = {
                                                         12,
                                                         12,
                                                         12
                                                       };
  jerry_register_magic_strings (magic_string_items, num_magic_string_items, magic_string_lengths);
}

See also

jerry_heap_stats

Summary

Get heap memory stats.

Notes:

  • The engine must be initialized with the JERRY_INIT_MEM_STATS option to allow heap statistic collections. See jerry_init
  • This API depends on a build option (JERRY_MEM_STATS) and can be checked in runtime with the JERRY_FEATURE_HEAP_STATS feature enum value, see: jerry_feature_enabled.

Prototype

bool
jerry_heap_stats (jerry_heap_stats_t *out_stats_p);
  • out_stats_p - out parameter, that provides the heap statistics.
  • return value
    • true, if stats were written into the out_stats_p pointer.
    • false, otherwise. Usually it is because the JERRY_FEATURE_HEAP_STATS feature is not enabled.

New in version 2.0.

Example

jerry_init (JERRY_INIT_MEM_STATS);
// ...

jerry_heap_stats_t stats = {0};
bool get_stats_ret = jerry_heap_stats (&stats);

See also

jerry_heap_gc

Summary

Performs garbage collection.

Prototype

void
jerry_heap_gc (jerry_gc_mode_t mode);

Changed in version 2.0: Added mode argument.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t object_value = jerry_object ();
  jerry_value_free (object_value);

  jerry_heap_gc (JERRY_GC_PRESSURE_LOW);

  jerry_cleanup ();
}

See also

Parser and executor functions

Functions to parse and run JavaScript source code.

jerry_parse

Summary

Parse a script, module, or function and create a compiled code using a character string.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_parse (const jerry_char_t *source_p,
             size_t source_size,
             const jerry_parse_options_t *options_p);
  • source_p - string, containing source code to parse (must be a valid UTF8 string).
  • source_size - size of the string, in bytes.
  • options_p - additional parsing options, can be NULL if not used
  • return value
    • function object value, if script was parsed successfully,
    • thrown exception, otherwise

Changed in version 2.0: Added source_name_p, and source_name_length arguments.

Changed in version [[NEXT_RELEASE]]: The source_name_p, source_name_length, and parse_opts arguments are replaced by options_p. This function replaces the jerry_parse_function method.

Example 1

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  /* Parsing a script. */
  const jerry_char_t script[] = "print ('Hello, World!');";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_STRICT_MODE | JERRY_PARSE_HAS_SOURCE_NAME | JERRY_PARSE_HAS_START;
  parse_options.source_name = jerry_string_sz ("hello.js");
  /* This example script is extracted from the middle of a file. */
  parse_options.start_line = 10;
  parse_options.start_column = 1;

  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  /* Run the "parsed_code" script with "jerry_run". */

  jerry_value_free (jerry_run (parsed_code));
  jerry_value_free (parsed_code);

  jerry_cleanup ();
  return 0;
}

Example - function parsing

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  /* Specify the argument list to parse a function. */
  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_ARGUMENT_LIST;
  parse_options.argument_list = jerry_string_sz ("a, b");

  const jerry_char_t function_code[] = "return a + b;";
  jerry_value_t parsed_function = jerry_parse (function_code, sizeof (function_code) - 1, &parse_options);
  jerry_value_free (parse_options.argument_list);

  /* Use the "parsed_function" as a normal JavaScript function. */

  jerry_value_t args[] = {
    jerry_number (3),
    jerry_number (4),
  };
  jerry_size_t argc = sizeof (args) / sizeof (args[0]);
  jerry_value_t call_result = jerry_call (parsed_function,
                                          jerry_undefined(),
                                          args,
                                          argc);

  /* use the function result */
  jerry_value_free (call_result);
  jerry_value_free (parsed_function);

  jerry_cleanup ();
  return 0;
}

See also

jerry_parse_value

Summary

Parse a script, module, or function and create a compiled code using a string value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_parse_value (const jerry_value_t source_value,
                   const jerry_parse_options_t *options_p);
  • source_value - string value, containing source code to parse (only string values are accepted).
  • options_p - additional parsing options, can be NULL if not used
  • return value
    • function object value, if script was parsed successfully,
    • thrown exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t script_value = jerry_string_sz ("print ('Hello, World!');");

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_STRICT_MODE | JERRY_PARSE_HAS_SOURCE_NAME | JERRY_PARSE_HAS_START;
  parse_options.source_name = jerry_string_sz ("hello.js");
  /* This example script is extracted from the middle of a file. */
  parse_options.start_line = 10;
  parse_options.start_column = 1;

  jerry_value_t parsed_code = jerry_parse_value (script_value, &parse_options);
  jerry_value_free (parse_options.source_name);
  jerry_value_free (script_value);
  jerry_value_free (parsed_code);

  jerry_cleanup ();
  return 0;
}

See also

jerry_run

Summary

Run a Script or Module created by jerry_parse.

Notes:

  • The code should be previously parsed with jerry_parse.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_run (const jerry_value_t func_val);
  • func_val - function to run
  • return value
    • result of bytecode, if run was successful
    • thrown exception, otherwise

Example

#include "jerryscript.h"

int
main (void)
{
  const jerry_char_t script[] = "print ('Hello, World!');";

  /* Initialize engine */
  jerry_init (JERRY_INIT_EMPTY);

  /* Setup Global scope code */
  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, NULL);

  if (!jerry_value_is_exception (parsed_code))
  {
    /* Execute the parsed source code in the Global scope */
    jerry_value_t ret_value = jerry_run (parsed_code);

    /* Returned value must be freed */
    jerry_value_free (ret_value);
  }

  /* Parsed source code must be freed */
  jerry_value_free (parsed_code);

  /* Cleanup engine */
  jerry_cleanup ();
}

See also

jerry_eval

Summary

Perform JavaScript eval function call (ECMA-262 v5.1 sec-15.1.2.1).

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_eval (const jerry_char_t *source_p,
            size_t source_size,
            uint32_t parse_opts);
  • source_p - source code to evaluate, it must be a valid utf8 string.
  • source_size - length of the source code
  • parse_opts - combination of jerry_parse_option_enable_feature_t flags. The following flags are allowed: JERRY_PARSE_STRICT_MODE
  • return value - result of eval, may be an exception value.

Example

{
  jerry_value_t ret_val = jerry_eval (str_to_eval,
                                      strlen (str_to_eval),
                                      JERRY_PARSE_NO_OPTS);
}

See also

jerry_run_jobs

Summary

Run enqueued Promise tasks until the first thrown exception or until all tasks get executed.

Important Note: The task queue is not guaranteed to be empty after the function call has returned a value. Therefore, this function is best used in a while loop, handling each exception it returns, until the queue is empty.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_run_jobs (void)
  • return value - result of last executed job, may be an exception value.

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "new Promise(function(f,r) { f('Hello, World!'); }).then(function(x) { print(x); });";

  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, NULL);
  jerry_value_t script_value = jerry_run (parsed_code);

  jerry_value_t job_value;
  while (true)
  {
    job_value = jerry_run_jobs ();

    if (jerry_value_is_exception (job_value))
    {
      if (jerry_value_is_abort (job_value))
      {
        // Terminate the engine
      }

      // Handle the exception here
    }
    else
    {
      // The queue should be empty now
      break;
    }
  }

  jerry_value_free (job_value);
  jerry_value_free (script_value);
  jerry_value_free (parsed_code);

  jerry_cleanup ();
  return 0;
}

Get the global context

jerry_current_realm

Summary

Get the Global object.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_current_realm (void);
  • return value - api value of global object

Example

{
  jerry_value_t glob_obj_val = jerry_current_realm ();

  ... // Do something with global object, ex: add properties

  jerry_value_free (glob_obj_val);
}

See also

Checker functions

Functions to check the type of an API value (jerry_value_t).

jerry_value_is_abort

Summary

Returns whether the given jerry_value_t is an abort exception value.

Prototype

bool
jerry_value_is_abort (const jerry_value_t value);
  • value - api value
  • return value
    • true, if the given jerry_value_t is an abort exception
    • false, otherwise

New in version 2.0.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_abort (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_array

Summary

Returns whether the given jerry_value_t is an array.

Prototype

bool
jerry_value_is_array (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is an array
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_array (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_arraybuffer

Summary

Returns whether the given jerry_value_t is an ArrayBuffer object.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_arraybuffer (const jerry_value_t value)
  • value - api value to check.
  • return value
    • true, if the given jerry_value_t is an ArrayBuffer object.
    • false, otherwise

New in version 2.0.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_arraybuffer (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_shared_arraybuffer

Summary

Returns whether the given jerry_value_t is a SharedArrayBuffer object.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_shared_arraybuffer (const jerry_value_t value);
  • value - api value to check.
  • return value
    • true, if the given jerry_value_t is a SharedArrayBuffer object.
    • false, otherwise

New in version [[NEXT_RELEASE]].

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_shared_arraybuffer (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_boolean

Summary

Returns whether the given jerry_value_t is a boolean value.

Prototype

bool
jerry_value_is_boolean (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a boolean value
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_boolean (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_true

Summary

Returns whether the given jerry_value_t is a true value.

Prototype

bool
jerry_value_is_true (const jerry_value_t value);
  • value - api value
  • return value
    • true, if the given jerry_value_t is true value
    • false, otherwise

New in version [[NEXT_RELEASE]]. Replaces the jerry_get_boolean_value method.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_true (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_false

Summary

Returns whether the given jerry_value_t is a false value.

Prototype

bool
jerry_value_is_false (const jerry_value_t value);
  • value - api value
  • return value
    • true, if the given jerry_value_t is false value
    • false, otherwise

New in version [[NEXT_RELEASE]].

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_false (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_constructor

Summary

Returns whether the given jerry_value_t is a constructor function.

Prototype

bool
jerry_value_is_constructor (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a constructor
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_constructor (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_dataview

Summary

Returns whether the given jerry_value_t is a DataView object value.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_DATAVIEW) and can be checked in runtime with the JERRY_FEATURE_DATAVIEW feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_dataview (const jerry_value_t value)
  • value - API value
  • return value
    • true, if the given jerry_value_t is a DataView object
    • false, otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t arraybuffer = jerry_arraybuffer (16);
  jerry_value_t dataview = jerry_dataview (arraybuffer, 0, 16);

  if (jerry_value_is_dataview (dataview))
  {
    // usage of dataview
  }

  jerry_value_free (dataview);
  jerry_value_free (arraybuffer);

  jerry_cleanup ();
  return 0;
}

See also

jerry_value_is_exception

Summary

Returns whether the given jerry_value_t is an exception value.

Prototype

bool
jerry_value_is_exception (const jerry_value_t value);
  • value - api value
  • return value
    • true, if the given jerry_value_t is an exception value.
    • false, otherwise

New in version 2.0.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_exception (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_function

Summary

Returns whether the given jerry_value_t is a function.

Prototype

bool
jerry_value_is_function (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a function
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_function (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_async_function

Summary

Returns whether the given jerry_value_t is an async function.

Prototype

bool
jerry_value_is_async_function (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is an async function
    • false, otherwise

New in version 2.4.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_async_function (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_number

Summary

Returns whether the given jerry_value_t is a number.

Prototype

bool
jerry_value_is_number (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a number
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_number (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_null

Summary

Returns whether the given jerry_value_t is a null value.

Prototype

bool
jerry_value_is_null (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a null
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_null (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_object

Summary

Returns whether the given jerry_value_t is an object value.

Prototype

bool
jerry_value_is_object (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is an object
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_object (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_promise

Summary

Returns whether the given jerry_value_t is a promise value.

Prototype

bool
jerry_value_is_promise (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a promise
    • false, otherwise

New in version 2.0.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_promise (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_proxy

Summary

Returns whether the given jerry_value_t is a proxy value.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_PROXY) and can be checked in runtime with the JERRY_FEATURE_PROXY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_proxy (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a proxy object
    • false, otherwise

New in version 2.3.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_proxy (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_string

Summary

Returns whether the given jerry_value_t is a string value.

Prototype

bool
jerry_value_is_string (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is a string
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_string (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_is_symbol

Summary

Returns whether the given jerry_value_t is a symbol value.

Prototype

bool
jerry_value_is_symbol (const jerry_value_t value)
  • value - API value
  • return value
    • true, if the given jerry_value_t is a symbol
    • false, otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t string_value = jerry_string_sz ("Symbol description string");
  jerry_value_t symbol_value = jerry_symbol_with_description (string_value);

  jerry_value_free (string_value);

  if (jerry_value_is_symbol (symbol_value))
  {
    // usage of symbol_value
  }

  jerry_value_free (symbol_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_value_is_bigint

Summary

Returns whether the given jerry_value_t is a bigint value.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_BIGINT) and can be checked in runtime with the JERRY_FEATURE_BIGINT feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_bigint (const jerry_value_t value)
  • value - API value
  • return value
    • true, if the given jerry_value_t is a BigInt
    • false, otherwise

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t string_value = jerry_string_sz ("12345678");
  jerry_value_t bigint_value = jerry_value_to_bigint (string_value);

  jerry_value_free (string_value);

  if (jerry_value_is_bigint (bigint_value))
  {
    // usage of bigint_value
  }

  jerry_value_free (bigint_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_value_is_typedarray

Summary

Checks whether the given jerry_value_t is a TypedArray object or not.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

bool
jerry_value_is_typedarray (const jerry_value_t value)
  • value - object to check
  • return value
    • true, if the given jerry_value_t is a TypedArray object.
    • false, otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t value = jerry_typedarray (JERRY_TYPEDARRAY_UINT16, 15);

  if (jerry_value_is_typedarray (value))
  {
    /* "value" is a typedarray. */
  }

  jerry_value_free (value);

  jerry_cleanup ();

  return 0;
}

See also

jerry_container_type

Summary

Checks whether the given jerry_value_t is the given jerry_container_type_t type container object.

Notes

  • This API function depends on a build option (JERRY_BUILTIN_CONTAINER) and can be checked runtime with the JERRY_FEATURE_MAP, JERRY_FEATURE_SET, JERRY_FEATURE_WEAKMAP, JERRY_FEATURE_WEAKSET feature enum values. see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_container_type_t
jerry_container_type (const jerry_value_t value)
  • value - Container object
  • return value
    • The corresponding enum value of jerry_container_type_t, or JERRY_CONTAINER_TYPE_INVALID if the container was not a valid container object.

New in version 2.3.

Example

#include "jerryscript.h"
int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t value = jerry_container (JERRY_CONTAINER_TYPE_MAP, NULL, 0);

  if (jerry_container_type (value) == JERRY_CONTAINER_TYPE_MAP)
  {
    /* "value" is a map. */
  }

  jerry_value_free (value);

  jerry_cleanup ();

  return 0;
}

See also

jerry_value_is_undefined

Summary

Returns whether the given jerry_value_t is an undefined value.

Prototype

bool
jerry_value_is_undefined (const jerry_value_t value)
  • value - api value
  • return value
    • true, if the given jerry_value_t is an undefined value
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_undefined (value))
  {
    ...
  }

  jerry_value_free (value);
}

See also

jerry_value_type

Summary

Returns the JavaScript type for a given value as a jerry_type_t enum value.

This is a similar operation to the ‘typeof’ operator in the standard with an exception that the ‘null’ value has its own enum value.

Prototype

jerry_type_t
jerry_value_type (const jerry_value_t value);
  • value - JavaScript value to check.
  • return value

New in version 2.0.

Example

{
  jerry_value_t number = jerry_number (3.3);

  jerry_type_t type_info = jerry_value_type (number);

  if (type_info == JERRY_TYPE_NUMBER)
  {
    /* ... */
  }

  jerry_value_free (number);
}

See also

jerry_object_type

Summary

Returns the object type for a given value as a jerry_object_type_t enum value.

Note: For non-object parameters JERRY_OBJECT_TYPE_NONE is returned. Note: the returned type can be checked for more detailed type information in the following cases:

Prototype

jerry_object_type_t
jerry_object_type (const jerry_value_t value);

New in version 2.4.

Example

{
  jerry_value_t object = jerry_object ();

  jerry_object_type_t object_type_info = jerry_object_type (object);

  if (type_info == JERRY_OBJECT_TYPE_GENERIC)
  {
    /* ... */
  }

  jerry_value_free (object);
}

See also

jerry_function_type

Summary

Returns the function type for a given value as a jerry_function_type_t enum value.

Prototype

jerry_function_type_t
jerry_function_type (const jerry_value_t value);

Note: For non-function parameters JERRY_FUNCTION_TYPE_NONE is returned.

New in version 2.4.

Example

{
  const jerry_char_t script[] = "function f() {}; f";
  jerry_value_t function_object = jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS);

  jerry_function_type_t function_type_info = jerry_function_type (function_object);

  if (type_info == JERRY_FUNCTION_TYPE_GENERIC)
  {
    /* ... */
  }

  jerry_value_free (function_object);
}

See also

jerry_iterator_type

Summary

Returns the iterator type for a given value as a jerry_iterator_type_t enum value.

Prototype

jerry_iterator_type_t
jerry_iterator_type (const jerry_value_t value);

Note: For non-iterator parameters JERRY_ITERATOR_TYPE_NONE is returned.

New in version 2.4.

Example

{
  const jerry_char_t script[] = "[1, 2, 3].values()";
  jerry_value_t iterator = jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS);

  jerry_iterator_type_t iterator_type_info = jerry_iterator_type (iterator);

  if (type_info == JERRY_ITERATOR_TYPE_ARRAY)
  {
    /* ... */
  }

  jerry_value_free (iterator);
}

See also

jerry_feature_enabled

Summary

Returns whether the specified compile time feature is enabled.

Prototype

bool
jerry_feature_enabled (const jerry_feature_t feature);
  • feature - jerry feature
  • return value
    • true, if the given jerry_feature_t is enabled
    • false, otherwise

New in version 2.0.

Example

{
  /* ... */
  jerry_feature_t feature = JERRY_FEATURE_SNAPSHOT_SAVE;

  if (jerry_feature_enabled (feature))
  {
    /* ... */
  }

}

See also

Binary operations

jerry_binary_op

Summary

Perform binary operation on the given operands (==, ===, <, >, etc.).

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_binary_op (jerry_binary_op_t op,
                 const jerry_value_t lhs,
                 const jerry_value_t rhs);
  • op - binary operation
  • lhs - left-hand side operand
  • rhs - right-hand side operand
  • return value
    • exception, if operation is unsuccessful or unsupported
    • the result of the binary operation on the given operands otherwise

New in version 2.0.

Example - JERRY_BIN_OP_EQUAL

{
  jerry_value_t value1;
  jerry_value_t value2;
  ... // create or copy value
  jerry_value_t result = jerry_binary_op (JERRY_BIN_OP_EQUAL, value1, value2)

  if (!jerry_value_is_exception (result))
  {
    if (jerry_value_is_true (result))
    {
       // value1 and value2 are equal
    }
    else
    {
      // value1 and value2 are NOT equal
    }
  }
  else
  {
    ... // handle error
  }

  jerry_value_free (value1);
  jerry_value_free (value2);
  jerry_value_free (result);
}

Example - JERRY_BIN_OP_INSTANCEOF

#include "jerryscript.h"

static jerry_value_t
my_constructor (const jerry_call_info_t *call_info_p,
                const jerry_value_t argv[],
                const jerry_length_t argc)
{
  return jerry_undefined ();
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t base_obj = jerry_object ();
  jerry_value_t constructor = jerry_function_external (my_constructor);

  /* External functions does not have a prototype by default, so we need to create one */
  jerry_value_t prototype_str = jerry_string_sz ("prototype");
  jerry_value_free (jerry_object_set (constructor, prototype_str, base_obj));
  jerry_value_free (prototype_str);

  /* Construct the instance. */
  jerry_value_t instance_val = jerry_construct (constructor, NULL, 0);

  /* Call the API function of 'instanceof'. */
  jerry_value_t is_instance = jerry_binary_op (JERRY_BIN_OP_INSTANCEOF,
                                               instance_val,
                                               constructor);
  if (!jerry_value_is_exception (is_instance)
      && jerry_value_is_true (is_instance))
  {
    /* ... */
  }

  /* Free all of the jerry values and cleanup the engine. */
  jerry_value_free (base_obj);
  jerry_value_free (constructor);
  jerry_value_free (instance_val);
  jerry_value_free (is_instance);

  jerry_cleanup ();
  return 0;
}

See also

Exception manipulation functions

Changed in version 2.0: The exception handling and manipulation was modified and the old methods were replaced.

jerry_throw_abort

Summary

Create (api) abort from a value.

This function creates an API abort value from an API value. The second argument defines whether the input value must be released or not. If it is set to true, then a jerry_value_free function will be called for the first argument, so the api value won’t be available after the call of jerry_throw_abort. The second argument should be false if both value and created abort value are needed.

Prototype

jerry_value_t
jerry_throw_abort (jerry_value_t value, bool take_ownersip);
  • value - api value
  • take_ownership - raw boolean, defines whether input value should be copied
  • return value - abort exception value

New in version 2.0.

Example 1

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t abort = jerry_throw_abort (value, true);
  // using the 'value' variable after release is invalid.

  jerry_value_free (abort);
}

Example 2

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t abort = jerry_throw_abort (value, false);
  // both 'abort' and 'value' can be used and must be released when they are no longer needed

  jerry_value_free (abort);
  jerry_value_free (value);
}

See also

jerry_throw

Summary

Create exception from a value.

This function creates an API exception value from an API value. The second argument defines whether the input value should be taken by the exception or copied. If it is set to true, then then the ownership of the argument value is taken, so it won’t be available after the call to jerry_throw. The second argument should be false if both the original value and created exception are needed.

Prototype

jerry_value_t
jerry_throw (jerry_value_t value, bool take_ownership);
  • value - api value
  • take_ownership - raw boolean, defines whether input value should be copied
  • return value - exception value

New in version 2.0.

Example 1

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t exception = jerry_throw (value, true);
  // using the 'value' variable after release is invalid.


  jerry_value_free (exception);
}

Example 2

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t exception = jerry_throw_value (value, false);
  // both 'exception' and 'value' can be used and must be released when they are no longer needed

  jerry_value_free (exception);
  jerry_value_free (value);
}

See also

jerry_error_type

Summary

Returns the type of the Error object if possible. If a non-error object is used as the input for the function the method will return JERRY_ERROR_NONE indicating that the value was not an Error object.

Note: If an exception value is passed as an argument, the function will inspect the contained value instead.

Prototype

jerry_error_t
jerry_error_type (const jerry_value_t value);
  • value - api value (possible exception object)
  • return value
    • JERRY_ERROR_NONE if the input is not an error object
    • one of the jerry_error_t value

New in version 2.0.

Example

{
  jerry_value_t error_obj = jerry_error_sz (JERRY_ERROR_RANGE, "error msg");
  jerry_error_t error_type = jerry_error_type (error_obj);

  // error_type is now JERRY_ERROR_RANGE.

  jerry_value_free (error_obj);
}

See also

jerry_exception_value

Summary

Get the value contained in an exception.

Many API functions cannot be called with an exception value. This function extracts the API value from an exception. The second argument defines whether the input exception value should be released or not. If it is set to true, then a jerry_value_free function will be called for the first argument, so the exception value won’t be available after the call of jerry_exception_value. The second argument should be false if both the exception and its contained value are needed.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_exception_value (jerry_value_t value, bool release)
  • value - exception value
  • release - raw boolean, defines whether input value must be released
  • return value - api value

New in version 2.0.

Example 1

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t exception = jerry_throw_value (value, true);
  jerry_value_t value_from_error = jerry_exception_value (exception, true);
  // using the 'exception' variable after release is invalid.

  jerry_value_free (value_from_error);
}

Example 2

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t exception = jerry_throw_value (value, true);
  jerry_value_t value_from_error = jerry_exception_value (exception, false);
  // both 'exception' and 'value_from_error' can be used and must be released when they are no longer needed

  jerry_value_free (value_from_error);
  jerry_value_free (exception);
}

See also

jerry_error_on_created

Summary

Set the decorator callback for newly created Error objects. The operation of the callback is described in jerry_error_object_created_cb_t.

Prototype

void jerry_error_on_created (jerry_error_object_created_cb_t callback, void *user_p);
  • callback - callback function, the previously set value is overwritten, and setting NULL disables the operation
  • user_p - pointer passed to the callback function, can be NULL

New in version 2.4.

Example

static void
error_object_created_callback (const jerry_value_t error_object) /**< new error object */
                               void *user_p) /**< user pointer */
{
  (void) error_object;
  (void) user_p;
  printf ("Notification: a new error is created\n");
} /* error_object_created_callback */

void main(void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_error_on_created (error_object_created_callback, NULL);

  jerry_value_free (jerry_error_sz (JERRY_ERROR_COMMON, "Message"));

  jerry_cleanup ();
} /* main */

See also

jerry_on_throw

Summary

The callback passed to this function is called when an exception is thrown in ECMAScript code. The callback is not called again until the value is caught. See: jerry_throw_cb_t.

Notes:

  • This API depends on a build option (JERRY_VM_THROW) and can be checked in runtime with the JERRY_FEATURE_VM_THROW feature enum value, see: jerry_feature_enabled.

Prototype

void
jerry_on_throw (jerry_throw_cb_t throw_cb,
                void *user_p);
  • throw_cb - callback which is called on throws (passing NULL disables this feature)
  • user_p - user pointer passed to the throw_cb function

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

static void
vm_throw_callback (const jerry_value_t error_value, /**< captured exception */
                   void *user_p) /**< user pointer */
{
  (void) error_value;

  /* Counts the number of throws. */
  int *counter_p = (int *) user_p;
  (*counter_p)++;
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  int counter = 0;
  jerry_on_throw (vm_throw_callback, &counter);

  const jerry_char_t script[] = "try { throw new Error('1') } catch (e) { throw new Error('2') }";

  jerry_value_free (jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS));

  /* The counter contains 2. */

  jerry_cleanup ();
  return 0;
}

See also

jerry_exception_is_captured

Summary

Checks whether the callback set by jerry_on_throw captured the exception.

Notes:

  • This API depends on a build option (JERRY_VM_THROW) and can be checked in runtime with the JERRY_FEATURE_VM_THROW feature enum value, see: jerry_feature_enabled.

Prototype

bool jerry_exception_is_captured (jerry_value_t value);
  • value - api value (should be an exception)
  • return value
    • true, if the vm throw callback captured the exception
    • false, otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

static void
vm_throw_callback (const jerry_value_t error_value, /**< captured exception */
                   void *user_p) /**< user pointer */
{
  (void) error_value;
  (void) user_p;
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  int counter = 0;
  jerry_on_throw (vm_throw_callback, &counter);

  const jerry_char_t script[] = "throw new Error()";
  jerry_value_t result_value = jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS);

  if (jerry_exception_is_captured (result_value))
  {
    /* Code enters here, because the vm_throw_callback function is called. */
  }

  jerry_value_free (result_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_exception_allow_capture

Summary

Sets whether the callback set by jerry_on_throw should capture the exception or not.

Notes:

  • This API depends on a build option (JERRY_VM_THROW) and can be checked in runtime with the JERRY_FEATURE_VM_THROW feature enum value, see: jerry_feature_enabled.

Prototype

void jerry_exception_allow_capture (jerry_value_t value, bool should_capture);
  • value - api value (should be an exception)
  • should_capture - callback should capture this error

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

static void
vm_throw_callback (const jerry_value_t error_value, /**< captured exception */
                   void *user_p) /**< user pointer */
{
  (void) error_value;
  (void) user_p;
}

static jerry_value_t
throw_exception (const jerry_call_info_t *call_info_p, /**< call info */
                 const jerry_value_t argv[], /**< argument list */
                 const jerry_length_t argc) /**< argument count */
{
  (void) call_info_p;
  (void) argv;
  (void) argc;

  jerry_value_t result_value = jerry_throw_sz (JERRY_ERROR_COMMON, "Error!");

  /* Ignore calling the vm_throw_callback function. */
  jerry_exception_allow_capture (result_value, false);
  return result_value;
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  int counter = 0;
  jerry_on_throw (vm_throw_callback, &counter);

  jerry_value_t global_object_value = jerry_current_realm ();
  jerry_value_t function_value = jerry_function_external (throw_exception);
  jerry_value_t function_name_value = jerry_string_sz ("throw_exception");

  jerry_value_free (jerry_object_set (global_object_value, function_name_value, function_value));
  jerry_value_free (function_name_value);
  jerry_value_free (function_value);
  jerry_value_free (global_object_value);

  const jerry_char_t script[] = "throw_exception()";
  jerry_value_free (jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS));

  jerry_cleanup ();
  return 0;
}

See also

Getter functions of ‘jerry_value_t’

Get raw data from API values.

jerry_value_as_number

Summary

Gets the number value of the given jerry_value_t parameter as a raw double.

If the argument passed is not a number 0.0 will be returned.

Prototype

double
jerry_value_as_number (const jerry_value_t value);
  • value - api value
  • return value
    • the number value of the given jerry_value_t parameter as a raw double.
    • 0.0 if the api value passed is not a number.

Example

{
  jerry_value_t value;
  ... // create or copy value

  if (jerry_value_is_number (value))
  {
    double raw_value = jerry_value_as_number (value);

    ... // usage of raw value

  }

  jerry_value_free (value);
}

See also

Functions for string values

jerry_string_size

Summary

Get the size of a string. Returns zero, if the value parameter is not a string. This is effectively the number of bytes required to store the string’s characters.

Prototype

jerry_size_t
jerry_string_size (const jerry_value_t value, JERRY_ENCODING_CESU8);
  • value - api value
  • return value - number of bytes in the buffer needed to represent the string.

Example

{
  const char char_array[] = "a string";
  jerry_value_t string = jerry_string_sz (char_array);

  jerry_size_t string_size = jerry_string_size (string, JERRY_ENCODING_CESU8);

  ... // usage of string_size

  jerry_value_free (string);
}

See also

jerry_string_length

Summary

Get the length of a string. Returns zero, if the value parameter is not a string.

Notes:

  • The difference from jerry_string_size is that it returns the number of bytes used for the string.
  • This is not the number of bytes required to store the string.

Prototype

jerry_length_t
jerry_string_length (const jerry_value_t value);
  • value - api value
  • return value - number of characters in the string

Example

{
  const char char_array[] = "a string";
  jerry_value_t string = jerry_string_sz (char_array);

  jerry_length_t string_length = jerry_string_length (string);

  ... // usage of string_length

  jerry_value_free (string);
}

See also

jerry_string_to_buffer

Summary

Copy the characters of a string into a specified cesu-8 buffer. The ‘\0’ character could occur in the character buffer. Returns 0, if the input value is not a string.

Note: Does not put ‘\0’ to the end of string, the return value identifies the number of valid bytes in the output buffer.

Note: If the size of the string is larger than the size of the target buffer, the string will be cropped.

Prototype

jerry_size_t
jerry_string_to_buffer (const jerry_value_t value,
                        jerry_encoding_t encoding,
                        jerry_char_t *buffer_p,
                        jerry_size_t buffer_size);
  • value - input string value
  • encoding - encoding oh the string data
  • buffer_p - pointer to output buffer
  • buffer_size - size of the buffer
  • return value - number of bytes copied to the buffer

Example

#include <stdio.h>
#include <stdlib.h>
#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t value;
  // create or copy value
  value = jerry_string_sz ("Demo string");

  // Read the string into a byte buffer.
  jerry_size_t string_size = jerry_string_size (value, JERRY_ENCODING_CESU8);
  jerry_char_t *string_buffer_p = (jerry_char_t *) malloc (sizeof (jerry_char_t) * (string_size + 1));

  jerry_size_t copied_bytes = jerry_string_to_buffer (value, JERRY_ENCODING_CESU8, string_buffer_p, string_size);
  string_buffer_p[copied_bytes] = '\0';

  jerry_value_free (value);

  jerry_cleanup ();

  printf ("Test string: %s\n", string_buffer_p);
  free (string_buffer_p);

  return 0;
}

See also

jerry_string_external_on_free

Summary

Sets the global callback which is called when the string data of an external string is no longer used. It is recommended to set this function before the first external string is created.

Note:

  • When the callback is NULL, no function is called when an external string is freed.
  • In some cases (e.g. when the string is also a magic string registered by jerry_register_magic_strings), the callback is called when the string is created, not when it is released.

Prototype

void jerry_string_external_on_free (jerry_external_string_free_cb_t callback_p);
  • callback_p - callback which is called when an external string is freed.

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"
#include <stdio.h>

static void
external_string_free_callback (jerry_char_t *string_p, /**< string pointer */
                               jerry_size_t string_size, /**< size of the string */
                               void *user_p) /**< user pointer */
{
  printf ("External string is freed!\n");
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_string_external_on_free (external_string_free_callback);

  const char *string_p = "This is a long external string, should not be duplicated!";
  jerry_value_t external_string = jerry_string_external_sz (string_p, NULL);
  /* The external_string_free_callback is called. */
  jerry_value_free (external_string);

  jerry_cleanup ();
  return 0;
}

See also

jerry_string_user_ptr

Summary

Returns the user pointer assigned to an external string.

Note:

Prototype

void *jerry_string_user_ptr (const jerry_value_t value,
                             bool *is_external);
  • value - string value.
  • is_external - when is_external is non-NULL, the referenced boolean value is set to true, if value is an external string, and set to false otherwise
  • return value
    • user pointer - if value argument is an external string
    • NULL - otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"
#include <stdio.h>

static int user_value = 1;

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const char *string_p = "This is a long external string, should not be duplicated!";

  jerry_value_t external_string = jerry_string_external_sz (string_p, (void *) &user_value);

  bool is_external;
  void *user_p = jerry_string_user_ptr (external_string, &is_external);

  if (is_external)
  {
    /* Prints the address of user_value. */
    printf("User pointer of an external string: %p\n", user_p);
  }

  jerry_value_free (external_string);

  jerry_cleanup ();
  return 0;
}

See also

Functions for array object values

jerry_array_length

Summary

Get length of an array object. Returns zero, if the given parameter is not an array object.

Prototype

uint32_t
jerry_array_length (const jerry_value_t value);
  • value - input array value
  • return value - length of the given array

Example

{
  jerry_value_t value;
  ... // create or copy value

  uint32_t len = jerry_array_length (value);

  jerry_value_free (value);
}

See also

Converters of ‘jerry_value_t’

Functions for converting API values to another value type.

jerry_value_to_boolean

Summary

Call ToBoolean operation on the api value.

Prototype

bool
jerry_value_to_boolean (const jerry_value_t value);
  • value - api value
  • return value
    • true, if the logical value is true
    • false, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  bool b = jerry_value_to_boolean (value);

  jerry_value_free (value);
}

See also

jerry_value_to_number

Summary

Call ToNumber operation on the api value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_to_number (const jerry_value_t value);
  • value - api value
  • return value
    • converted number value, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t number_value = jerry_value_to_number (value);

  jerry_value_free (number_value);
  jerry_value_free (value);
}

See also

jerry_value_to_object

Summary

Call ToObject operation on the api value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_to_object (const jerry_value_t value);
  • value - api value
  • return value
    • converted object value, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t object_value = jerry_value_to_object (value);

  jerry_value_free (object_value);
  jerry_value_free (value);
}

See also

jerry_value_to_primitive

Summary

Call ToPrimitive operation on the api value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_to_primitive (const jerry_value_t value);
  • value - api value
  • return value
    • converted primitive value, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t prim_value = jerry_value_to_primitive (value);

  jerry_value_free (prim_value);
  jerry_value_free (value);
}

See also

jerry_value_to_string

Summary

Call the ToString ecma builtin operation on the api value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_to_string (const jerry_value_t value);
  • value - api value
  • return value
    • converted string value, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t string_value = jerry_value_to_string (value);

  jerry_value_free (string_value);
  jerry_value_free (value);
}

See also

jerry_value_to_bigint

Summary

Call the BigInt constructor ecma builtin operation on the api value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_to_bigint (const jerry_value_t value);
  • value - api value
  • return value
    • converted BigInt value, if success
    • thrown exception, otherwise

New in version 2.4.

Example

{
  jerry_value_t value;
  ... // create or copy value

  jerry_value_t bigint_value = jerry_value_to_bigint (value);

  jerry_value_free (bigint_value);
  jerry_value_free (value);
}

See also

jerry_value_as_integer

Summary

Convert any number to integer number. Returns 0 if value is not number. Based on ECMA 262 v11 7.1.5

Prototype

double
jerry_value_as_integer (const jerry_value_t value);
  • value - api value
  • return
    • 0, if value is not a number
    • integer representation of the number, otherwise

New in version 2.4.

Example

{
  jerry_value_t number_val = jerry_number (123321);
  double number = jerry_value_as_integer (number_val);
  jerry_value_free (number_val);
}

jerry_value_as_int32

Summary

Convert any number to int32 number. Returns 0 if value is not number. Based on ECMA 262 v11 7.1.6

Prototype

int32_t
jerry_value_as_int32 (const jerry_value_t value);
  • value - api value
  • return
    • 0, if value is not a number
    • int32 representation of the number, otherwise

New in version 2.4.

Example

{
  jerry_value_t number_val = jerry_number (123321);
  int32_t number = jerry_value_as_int32 (number_val);
  jerry_value_free (number_val);
}

jerry_value_as_uint32

Summary

Convert any number to uint32 number. Returns 0 if value is not number. Based on ECMA 262 v11 7.1.7

Prototype

uint32_t
jerry_value_as_uint32 (const jerry_value_t value);
  • value - api value
  • return
    • 0, if value is not a number
    • uint32 representation of the number, otherwise

New in version 2.4.

Example

{
  jerry_value_t number_val = jerry_number (123321);
  uint32_t number = jerry_value_as_uint32 (number_val);
  jerry_value_free (number_val);
}

Functions for module objects

These APIs all depend on module support.

Summary

Link modules to their dependencies. The dependencies are resolved by a user callback.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t jerry_module_link (const jerry_value_t module_val,
                                 jerry_module_resolve_cb_t callback, void *user_p)
  • module_val - module object in unlinked state
  • callback - user callback which is called to resolve dependencies, uses jerry_port_module_resolve when NULL is passed
  • user_p - user pointer passed to the callback
  • return
    • true - if linking is successful
    • exception - otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>

static jerry_value_t
module_resolve_callback (const jerry_value_t specifier,
                         const jerry_value_t referrer,
                         void *user_data_p)
{
  /* In this case, the specifier contains 'b.mjs', and the referrer is the module
   * created in the main() function below. Normally the specifier string should be
   * extended to a full file system path, and it should be checked whether a module
   * corresponding to this path has been loaded already. For simplicity, this function
   * returns with a new module. */

  const jerry_char_t script[] = "export var a = 5";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("b.mjs");

  jerry_value_t result = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);
  return result;
} /* module_resolve_callback */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "import a from 'b.mjs'";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t ret_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  jerry_module_link (ret_value, module_resolve_callback, NULL);

  jerry_value_free (ret_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_evaluate

Evaluate a module and its dependencies. The module must be in linked state.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t jerry_module_evaluate (const jerry_value_t module_val);
  • module_val - module object
  • return
    • result of module bytecode execution - if evaluation was successful
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "export var a = 6";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  jerry_value_free (jerry_module_link (module_value, NULL, NULL));
  jerry_value_free (jerry_module_evaluate (module_value));

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_state

Summary

Returns the current status of a module. The available values are listed in jerry_module_state_t

Notes:

  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_module_state_t jerry_module_state (const jerry_value_t module_val);
  • module_val - module object
  • return
    • current status - if module_val is a module
    • JERRY_MODULE_STATE_INVALID - otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "import a from 'b.mjs'";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  if (jerry_module_state (module_value) == JERRY_MODULE_STATE_UNLINKED)
  {
    printf ("Module parsing has been successful\n");
  }

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_on_state_changed

Summary

Sets a callback which is called after a module state is changed to linked, evaluated, or error.

Notes:

  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

void jerry_module_on_state_changed (jerry_module_state_changed_cb_t callback,
                                    void *user_p);
  • callback - callback, which is called after the state change.
  • user_p - pointer passed to the callback function.

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

static void
module_state_changed (jerry_module_state_t new_state, /**< new state of the module */
                      const jerry_value_t module_val, /**< a module whose state is changed */
                      const jerry_value_t value, /**< value argument */
                      void *user_p) /**< user pointer */
{
  (void) module_val;
  (void) value;
  (void) user_p;

  if (new_state == JERRY_MODULE_STATE_LINKED)
  {
    printf ("A module is entered into linked state\n");
  }
} /* module_state_changed */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "12";

  jerry_module_on_state_changed (module_state_changed, NULL);

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  jerry_value_free (jerry_module_link (module_value, NULL, NULL));

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_on_import_meta

Summary

Sets a callback which is called when an import.meta expression of a module is evaluated the first time.

Notes:

  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

void jerry_module_on_import_meta (jerry_module_import_meta_cb_t callback,
                                  void *user_p);
  • callback - callback, which is called when an import.meta expression of a module is evaluated the first time
  • user_p - pointer passed to the callback function.

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

static void
module_import_meta_callback (const jerry_value_t module, /**< module */
                             const jerry_value_t meta_object, /**< import.meta object */
                             void *user_p) /**< user pointer */
{
  (void) user_p;

  /* Create a property for the meta object */
  jerry_value_t property_name_value = jerry_string_sz ("prop");
  jerry_value_t property_value = jerry_string_sz ("prop");
  jerry_value_t result_value = jerry_object_set (meta_object, property_name_value, property_value);
  jerry_value_free (result_value);
  jerry_value_free (property_value);
  jerry_value_free (property_name_value);
} /* module_import_meta_callback */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "import.meta";

  jerry_module_on_import_meta (module_import_meta_callback, NULL);

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE;

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);

  jerry_value_free (jerry_module_link (module_value, NULL, NULL));
  jerry_value_free (jerry_module_evaluate (module_value));

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_request_count

Summary

Returns the number of import/export requests of a module. The requests can be queried by jerry_module_request.

Notes:

  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

size_t jerry_module_request_count (const jerry_value_t module_val);
  • module_val - module object
  • return
    • number of import/export requests of a module, if module_val is module,
    • 0, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "export * from 'b.mjs'"
                                "import a from 'c.mjs'";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  /* Prints 2. */
  printf ("Number of requests: %d\n", (int) jerry_module_request_count (module_value));

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_request

Summary

Returns the module request specified by the request_index argument. The requests are ordered in source code occurrence. When parsing is completed, all returned values are strings. If jerry_module_link is completed successfully all returned values are module objects instead. If linking is in progress or fails, the successfully resolved dependencies are module objects, the rest are strings. The number of requests can be queried by jerry_module_request_count.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t jerry_module_request (const jerry_value_t module_val, size_t request_index);
  • module_val - module object
  • return
    • string, if the request has not been resolved yet
    • module object, if the request has been resolved successfully
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "export * from 'b.mjs'"
                                "import a from 'c.mjs'";
  const jerry_char_t file[] = "a.mjs";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  jerry_value_t request_value = jerry_module_request (module_value, 0);
  /* Returns with b.mjs */
  jerry_value_free (request_value);

  request_value = jerry_module_request (module_value, 1);
  /* Returns with c.mjs */
  jerry_value_free (request_value);

  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_namespace

Returns the namespace object of a module

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t jerry_module_namespace (const jerry_value_t module_val);
  • module_val - module object
  • return
    • object, if namespace object is available
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "export var a = 6";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("a.mjs");

  jerry_value_t module_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);

  jerry_value_free (jerry_module_link (module_value, NULL, NULL));
  jerry_value_free (jerry_module_evaluate (module_value));

  jerry_value_t namespace_value = jerry_module_namespace (module_value);

  /* Exports can be checked. */

  jerry_value_free (namespace_value);
  jerry_value_free (module_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_module_on_import

Sets the callback which is called when dynamic imports are resolved. The resolver receives the user_value assigned to the currently executed script, which should provide all the information that is necessary for the resolve.

Notes:

  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.
  • The possible return values of the callback is explained in jerry_module_import_cb_t

Prototype

void
jerry_module_on_import (jerry_module_import_cb_t callback_p,
                        void *user_p)
  • callback_p - a jerry_module_import_cb_t callback which handles import() calls
  • user_p - user pointer passed to the callback

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>
#include <stdio.h>

typedef struct {
  jerry_value_t specifier;
  jerry_value_t user_value;
  jerry_value_t promise;
} resolve_module_task_t;

static jerry_value_t
resolve_dynamic (const jerry_value_t specifier, /**< module specifier */
                 const jerry_value_t user_value, /**< user value assigned to the script */
                 void *user_p) /**< user data */
{
  /* If the specified module has already been evaluated, this callback can
   * return with it and the promise creation is automatically done by the engine.
   * Otherwise the application usually adds a resolve task to a command queue. */

  /* This very simple command queue supports only one task. */
  resolve_module_task_t *task_p = (resolve_module_task_t *) user_p;
  task_p->specifier = jerry_value_copy (specifier);
  task_p->user_value = jerry_value_copy (user_value);

  /* This Promise should be evaluated later. */
  jerry_value_t promise = jerry_promise ();
  task_p->promise = jerry_value_copy (promise);
  return promise;
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  resolve_module_task_t task;
  jerry_module_on_import (resolve_dynamic, &task);

  const jerry_char_t script[] = "import('modules/my_module.mjs').then(\n"
                                "  function (namespace) { /* use namespace */},\n"
                                "  function (error) { /* handle error */}\n"
                                ")";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_SOURCE_NAME | JERRY_PARSE_HAS_USER_VALUE;

  /* Resource is usually used for debugging purposes, e.g. for generating backtrace. */
  parse_options.source_name = jerry_string_sz ("dir/my_script.js");

  /* User value should provide information for resolving dynamic imports.
   * In this case it contains the full path excluding the filename. */
  parse_options.user_value = jerry_string_sz ("/home/user/dir");

  jerry_value_t script_value = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);
  jerry_value_free (parse_options.user_value);
  jerry_value_free (jerry_run (script_value));
  jerry_value_free (script_value);

  /* The application resolves both the module and the promise using the specifier
   * and the user_value. In this example the specifier is modules/my_module.mjs. */
  const jerry_char_t module_script[] = "export var a = 5";

  parse_options.options = JERRY_PARSE_MODULE | JERRY_PARSE_HAS_SOURCE_NAME | JERRY_PARSE_HAS_USER_VALUE;
  parse_options.source_name = jerry_string_sz ("modules/my_module.mjs");
  parse_options.user_value = jerry_string_sz ("/home/user/dir/modules");

  jerry_value_t module_value = jerry_parse (module_script, sizeof (module_script) - 1, &parse_options);
  jerry_value_free (parse_options.source_name);
  jerry_value_free (parse_options.user_value);
  jerry_value_free (jerry_module_link (module_value, NULL, NULL));
  jerry_value_free (jerry_module_evaluate (module_value));

  /* The promise must be resolved with the namespace object, not the module. */
  jerry_value_t namespace_value = jerry_module_namespace (module_value);
  jerry_value_free (jerry_promise_resolve (task.promise, namespace_value));

  jerry_value_free (namespace_value);
  jerry_value_free (module_value);
  jerry_value_free (task.specifier);
  jerry_value_free (task.user_value);
  jerry_value_free (task.promise);

  /* Process promise handlers. */
  jerry_value_free (jerry_run_jobs ());

  jerry_cleanup ();
  return 0;
}

See also

jerry_native_module

Creates a native module with a list of exports. The initial state of the module is linked.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • Native pointers can be used to assign private data to a native module, see jerry_object_set_native_ptr
  • When callback is NULL, no function is called when the module is evaluated, only its state is changed to evaluated.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t
jerry_native_module (jerry_native_module_evaluate_cb_t callback,
                     const jerry_value_t * const exports_p,
                     size_t number_of_exports);
  • callback - a jerry_native_module_evaluate_cb_t callback which is called by jerry_module_evaluate to evaluate the native module.
  • exports_p - list of the exported bindings of the module, must be valid string identifiers.
  • number_of_exports - number of exports in the exports_p list.
  • return
    • a native module, if the module is successfully created
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t exports[2] =
  {
    jerry_string_sz ("first_export"),
    jerry_string_sz ("second_export")
  };

  jerry_value_t native_module = jerry_native_module (NULL, exports, 2);

  jerry_value_free (exports[0]);
  jerry_value_free (exports[1]);
  jerry_value_free (native_module);

  jerry_cleanup ();
  return 0;
}

See also

jerry_native_module_get

Gets the value of an export binding which belongs to a native module.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t
jerry_native_module_get (const jerry_value_t native_module_val,
                         const jerry_value_t export_name_val);
  • native_module_val - a native module object.
  • export_name_val - string identifier of the export.
  • return
    • value of the export, if success
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t export = jerry_string_sz ("an_export");

  jerry_value_t native_module = jerry_native_module (NULL, &export, 1);

  jerry_value_t value = jerry_native_module_get (native_module, export);
  jerry_value_free (value);

  jerry_value_free (export);
  jerry_value_free (native_module);

  jerry_cleanup ();
  return 0;
}

See also

jerry_native_module_set

Sets the value of an export binding which belongs to a native module.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_MODULE_SYSTEM) and can be checked in runtime with the JERRY_FEATURE_MODULE feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t
jerry_value_t jerry_native_module_set (const jerry_value_t native_module_val,
                                       const jerry_value_t export_name_val,
                                       const jerry_value_t value_to_set)
  • native_module_val - a native module object.
  • export_name_val - string identifier of the export.
  • value_to_set - new value of the export.
  • return
    • true, if success
    • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include <jerryscript.h>

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t export = jerry_string_sz ("an_export");

  jerry_value_t native_module = jerry_native_module (NULL, &export, 1);

  jerry_value_t number = jerry_number (3.5);
  jerry_value_t value = jerry_native_module_set (native_module, export, number);
  jerry_value_free (value);
  jerry_value_free (number);

  jerry_value_free (export);
  jerry_value_free (native_module);

  jerry_cleanup ();
  return 0;
}

See also

Functions for promise objects

These APIs are always enabled.

jerry_promise_result

Summary

The function returns the result of a Promise object.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_promise_result (const jerry_value_t promise);
  • promise - the input Promise object.
  • return
    • The result of the Promise.
    • If the Promise is not resolved yet the result is the ‘undefined’ value.
    • A TypeError is returned if the input argument was not a Promise object or the Promise support was not built into the library.

New in version 2.2.

Example

#include <jerryscript.h>

static void
example (void)
{
  // create a promise object.
  jerry_value_t promise = jerry_promise ();
  {
    // prepare the argument for the resolve or reject.
    jerry_value_t argument = jerry_number (33);

    jerry_value_t is_ok = jerry_promise_resolve (promise, argument);

    // 'is_ok' should be checked if it is an exception or not.
    // skipped in this example
    jerry_value_free (is_ok);
    jerry_value_free (argument);
  }

  jerry_value_t promise_result = jerry_promise_result (promise);
  // 'promise_result' is now the number 33.

  jerry_value_free (promise_result);
  jerry_value_free (promise);
}

See also

jerry_promise_state

Summary

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_promise_state_t
jerry_promise_state (const jerry_value_t promise);
  • promise - the input promise object.
  • return
    • jerry_promise_state_t
    • JERRY_PROMISE_STATE_NONE is returned if the input argument was not a promise object or the Promise support was not built into the library.

New in version 2.2.

Example

#include <jerryscript.h>

static void
example (void)
{
  // create a promise object.
  jerry_value_t promise = jerry_promise ();

  jerry_promise_state_t start_state = jerry_promise_state (promise);
  // a Promise have a default state of JERRY_PROMISE_STATE_PENDING

  {
    // prepare the argument for the resolve or reject.
    jerry_value_t argument = jerry_number (33);

    jerry_value_t is_ok = jerry_promise_resolve (promise, argument);

    // 'is_ok' should be checked if it is an exception or not.
    // skipped in this example
    jerry_value_free (is_ok);
    jerry_value_free (argument);
  }

  jerry_promise_state_t current_state = jerry_promise_state (promise);
  // at this point the Promise should be in the JERRY_PROMISE_STATE_FULFILLED state.

  jerry_value_free (promise);
}

See also

jerry_promise_on_event

Summary

Sets a callback for tracking Promise and async operations.

Notes:

  • This API depends on a build option (JERRY_PROMISE_CALLBACK) and can be checked in runtime with the JERRY_FEATURE_PROMISE_CALLBACK feature enum value, see: jerry_feature_enabled.

Prototype

void jerry_promise_on_event (jerry_promise_event_filter_t filters, jerry_promise_event_cb_t callback,
                             void *user_p);
  • filters - combination of jerry_promise_event_filter_t options
  • callback - callback function, the previously set value is overwritten, and setting NULL disables the tracking
  • user_p - pointer passed to the callback function, can be NULL

New in version [[NEXT_RELEASE]].

Example

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static void
promise_callback (jerry_promise_event_type_t event_type, /**< event type */
                  const jerry_value_t object, /**< target object */
                  const jerry_value_t value, /**< optional argument */
                  void *user_p) /**< user pointer passed to the callback */
{
  if (event_type == JERRY_PROMISE_EVENT_CREATE)
  {
    printf ("A new promise is created\n");

    if (!jerry_value_is_undefined (value))
    {
      printf ("  The Promise is created by Promise.then() built-in.\n");
    }
  }
} /* promise_callback */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_promise_on_event (JERRY_PROMISE_EVENT_FILTER_CREATE, promise_callback, NULL);

  const char *source_p = "var p = Promise.resolve(0)\n"
                         "p.then(function (v) { return v; })";
  jerry_value_free (jerry_eval ((const jerry_char_t *) source_p,
                                strlen (source_p),
                                JERRY_PARSE_NO_OPTS));

  jerry_cleanup ();
  return 0;
} /* main */

See also

jerry_property_descriptor_to_object

Summary

This API function is equivalent to FromPropertyDescriptor operation defined in ECMA 262 v11 6.2.5.4. It returns with an ECMAScript Object which represents the property attributes.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_property_descriptor_to_object (const jerry_property_descriptor_t *src_prop_desc_p)
  • src_prop_desc_p - the input property descriptor.
  • return

New in version 2.4.

Example

#include <jerryscript.h>

static void
example (void)
{
  jerry_value_t prop_name = jerry_string_sz ("value");

  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  prop_desc.value = prop_name;
  prop_desc.flags |= JERRY_PROP_IS_VALUE_DEFINED;

  jerry_value_t from_object = jerry_property_descriptor_to_object (&prop_desc);

  jerry_value_free (prop_name);
  jerry_value_free (from_object);
  jerry_property_descriptor_free (&prop_desc);
}

jerry_property_descriptor_from_object

Summary

This API function is equivalent to ToPropertyDescriptor operation defined in ECMA 262 v11 6.2.5.5. It decodes the ECMAScript object and fills the fields of a JerryScript property descriptor.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_property_descriptor_from_object (jerry_value_t obj_value, jerry_property_descriptor_t *out_prop_desc_p);
  • obj_value - the input object
  • src_prop_desc_p - the output property descriptor.
  • return

New in version 2.4.

Example

#include <jerryscript.h>

static void
example (void)
{
  jerry_value_t object = jerry_object ();
  jerry_value_t prop_name = jerry_string_sz ("value");
  jerry_value_t value = jerry_boolean (true);
  jerry_property_descriptor_t prop_desc;

  jerry_value_free (jerry_object_set (object, prop_name, prop_name));

  jerry_value_free (jerry_property_descriptor_from_object (object, &prop_desc));

  jerry_value_free (object);
  jerry_value_free (prop_name);
  jerry_value_free (value);
  jerry_property_descriptor_free (&prop_desc);
}

jerry_promise_resolve

Summary

Resolve the promise with an argument.

Note:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_ESNEXT) and can be checked in runtime with the JERRY_FEATURE_PROMISE feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_promise_resolve (jerry_value_t promise, jerry_value_t argument);
  • promise - the promise value
  • argument - the argument value
  • return value
    • undefined - if resolve call was successful
    • exception - otherwise

New in version 2.0.

Changed in version [[NEXT_RELEASE]]: Build option dependency changed from JERRY_BUILTIN_PROMISE to JERRY_ESNEXT.

Example

{
  jerry_value_t promise = ... // create/copy a promise object.

  ...

  jerry_value_t argument = ... // prepare the argument for resolve.

  jerry_value_t is_ok = jerry_promise_resolve (promise, argument);

  if (jerry_value_is_exception (is_ok))
  {
    // handle the exception.
  }

  jerry_value_free (is_ok);
  jerry_value_free (argument);
  jerry_value_free (promise);
}

See also

jerry_promise_reject

Summary

Reject the promise with an argument.

Note:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_promise_reject (jerry_value_t promise, jerry_value_t argument);
  • promise - the promise value
  • argument - the argument value
  • return value
    • undefined - if reject call was successful
    • exception - otherwise

New in version 2.0.

Example

{
  jerry_value_t promise = ... // create/copy a promise object.

  ...

  jerry_value_t argument = ... // prepare the argument for reject.

  jerry_value_t is_ok = jerry_promise_reject (promise, argument);

  if (jerry_value_is_exception (is_ok))
  {
    // handle the exception.
  }

  jerry_value_free (is_ok);
  jerry_value_free (argument);
  jerry_value_free (promise);
}

See also

Functions for symbols

These APIs are always enabled.

jerry_symbol

Summary

Get the well-known symbol corresponding to the given well-known symbol id.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • If the symbol support is not enabled an undefined will be returned.

Prototype

jerry_value_t
jerry_symbol (jerry_well_known_symbol_t symbol);
  • symbol - jerry_well_known_symbol_t enum value
  • return value
    • undefined value - if invalid well-known symbol was requested
    • well-known symbol value, otherwise

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t array_value = jerry_array (5);
  jerry_value_t symbol_iterator = jerry_symbol (JERRY_SYMBOL_ITERATOR);
  jerry_value_t array_iterator = jerry_object_get (array_value, symbol_iterator);

  // usage of array_iterator

  jerry_value_free (array_iterator);
  jerry_value_free (symbol_iterator);
  jerry_value_free (array_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_symbol_description

Summary

Returns with the [[Description]] internal property of a symbol value.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_symbol_description (const jerry_value_t value);
  • value - symbol value
  • return value
    • string or undefined value containing the symbol’s description - if success
    • thrown exception, otherwise

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t string_value = jerry_string_sz ("foo");
  jerry_value_t symbol_value = jerry_symbol_with_description (string_value);

  jerry_value_free (string_value);

  jerry_value_t symbol_description = jerry_symbol_description (symbol_value);

  // usage of symbol_desc_string

  jerry_value_free (symbol_description);
  jerry_value_free (symbol_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_symbol_descriptive_string

Summary

Call the SymbolDescriptiveString ecma builtin operation on the API value. Based on ECMA 262 v6 19.4.3.2.1 this is in the form of Symbol(<description>).

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_symbol_descriptive_string (const jerry_value_t value);
  • value - symbol value
  • return value
    • string value containing the symbol’s descriptive string - if success
    • thrown exception, otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t string_value = jerry_string_sz ("foo");
  jerry_value_t symbol_value = jerry_symbol_with_description (string_value);

  jerry_value_free (string_value);

  jerry_value_t symbol_desc_string = jerry_symbol_descriptive_string (symbol_value);

  // usage of symbol_desc_string

  jerry_value_free (symbol_desc_string);
  jerry_value_free (symbol_value);

  jerry_cleanup ();
  return 0;
}

See also

Functions for BigInts

These APIs all depend on build option (JERRY_BUILTIN_BIGINT).

jerry_bigint_digit_count

Summary

Returns the size of uint64 digits of a BigInt value. This value is the minimum size of the buffer which can hold all digits of a BigInt value when the digits are retrieved by [jerry_bigint_to_digits](#jerry_bigint_to_digits).

Notes:

  • This API depends on a build option (JERRY_BUILTIN_BIGINT) and can be checked in runtime with the JERRY_FEATURE_BIGINT feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

uint32_t
jerry_bigint_digit_count (jerry_value_t value)
  • value - BigInt value
  • return value
    • number of digits (can be zero for BigInt zero)
    • if value is not a BigInt value, it returns with zero

New in version 2.4.

Example

#include <stdio.h>

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  uint64_t digits[4] = { 0x1, 0x1, 0x0, 0x0 };
  jerry_value_t bigint_value = jerry_bigint (digits, 4, true);

  /* Prints two, because the leading zeroes in digits buffer are discarded. */
  printf("size: %d\n", (int) jerry_bigint_digit_count (bigint_value));

  jerry_value_free (bigint_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_bigint_to_digits

Summary

Copies the uint64 digits of a BigInt value into a buffer. This function supports any buffer sizes. If the buffer size is smaller than the size returned by [jerry_bigint_digit_count](#jerry_bigint_digit_count), only the least significant digits are copied into the buffer. If the buffer size is greater, the unused digits are filled with zero.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_BIGINT) and can be checked in runtime with the JERRY_FEATURE_BIGINT feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

void
jerry_bigint_to_digits (jerry_value_t value, uint64_t *digits_p, uint32_t size, bool *sign_p)
  • value - BigInt value
  • digits_p - output buffer for digits
  • size - size of the output buffer
  • sign_p - the boolean passed to the function is set to false when the BigInt is positive, and set to true otherwise (this parameter can be NULL)

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  uint64_t digits[4] = { 0x1, 0x1, 0x0, 0x0 };
  jerry_value_t bigint_value = jerry_bigint (digits, 4, true);

  uint64_t get_digits[4];
  bool sign;
  jerry_bigint_to_digits (bigint_value, get_digits, 2, &sign);

  jerry_value_free (bigint_value);

  jerry_cleanup ();
  return 0;
}

See also

Functions for Proxy objects

These APIs all depend on build option (JERRY_BUILTIN_PROXY).

jerry_proxy_target

Summary

Gets the target object of a Proxy object.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_PROXY) and can be checked in runtime with the JERRY_FEATURE_PROXY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_proxy_target (jerry_value_t proxy_value);
  • proxy_value - Proxy object value
  • return value
    • type error exception - if proxy_value is not a Proxy object
    • target object - otherwise

New in version 2.4.

Example

{
  jerry_value_t target = jerry_object ();
  jerry_value_t handler = jerry_object ();
  jerry_value_t proxy = jerry_proxy (target, handler);

  jerry_value_free (target);
  jerry_value_free (handler);

  target = jerry_proxy_target (proxy);

  // ... usage of the target

  jerry_value_free (target);
  jerry_value_free (proxy);
}

See also

jerry_proxy_handler

Summary

Gets the handler object of a Proxy object.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_PROXY) and can be checked in runtime with the JERRY_FEATURE_PROXY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_proxy_handler (jerry_value_t proxy_value);
  • proxy_value - Proxy object value
  • return value
    • type error exception - if proxy_value is not a Proxy object
    • handler object - otherwise

New in version [[NEXT_RELEASE]].

Example

{
  jerry_value_t target = jerry_object ();
  jerry_value_t handler = jerry_object ();
  jerry_value_t proxy = jerry_proxy (target, handler);

  jerry_value_free (target);
  jerry_value_free (handler);

  handler = jerry_proxy_handler (proxy);

  // ... usage of the handler

  jerry_value_free (handler);
  jerry_value_free (proxy);
}

See also

Copy and free API values

jerry_value_copy

Summary

Copies the specified Jerry API value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_value_copy (jerry_value_t value);
  • value - api value
  • return value - copied value

Example

{
  jerry_value_t object_value = jerry_object ();

  jerry_value_t copied_object = jerry_value_copy (object_value);

  jerry_value_free (object_value);

  // copied_object refers to the created object and makes it
  // available after the release of 'object_value'

  jerry_value_free (copied_object);
}

See also

jerry_value_free

Summary

Release specified Jerry API value.

Prototype

void
jerry_value_free (jerry_value_t value);
  • value - api value

Example

{
  jerry_value_t object_value = jerry_object ();

  ...

  jerry_value_free (object_value);
}

Create API values

Function for creating API values.

Note: Every created API value must be freed with jerry_value_free when it is no longer needed.

jerry_array

Summary

Create an array object value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_array (uint32_t size);
  • size - size of array;
  • return value - value of the constructed array object

Example

{
    jerry_value_t array = jerry_array (10);

    ...

    jerry_value_free (array);
}

See also

jerry_arraybuffer

Summary

Create a jerry_value_t representing an ArrayBuffer object.

Note:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_arraybuffer (jerry_length_t size);
  • size - size of the backing store allocated for the array buffer in bytes.
  • return value - the new ArrayBuffer as a jerry_value_t

New in version 2.0.

Example

{
  jerry_value_t buffer_value = jerry_arraybuffer (15);

  ... // use the ArrayBuffer

  jerry_value_free (buffer_value);
}

See also

jerry_arraybuffer_external

Summary

Creates a jerry_value_t representing an ArrayBuffer object with user specified back-buffer.

User must pass a buffer pointer which is at least size big. After the object is not needed the GC will call the free_cb so the user can release the buffer which was provided.

Note:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • If buffer_p is NULL, the buffer is allocated by the allocator callback passed to jerry_arraybuffer_allocator
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_arraybuffer_external (uint8_t *buffer_p,
                            const jerry_length_t size
                            void *arraybuffer_user_p);
  • size - size of the buffer in bytes.
  • buffer_p - the backing store used by the array buffer object.
  • arraybuffer_user_p - user pointer assigned to the array buffer object.
  • return value
    • value of the newly constructed array buffer object.

New in version 2.0.

Changed in version [[NEXT_RELEASE]]: free_cb has been replaced by arraybuffer_user_p.

Example

{
  uint8_t buffer_p[15];
  jerry_value_t buffer_value = jerry_arraybuffer_external (buffer_p, 15, NULL);

  ... // use the array buffer

  jerry_value_free (buffer_value);
}

See also

jerry_shared_arraybuffer

Summary

Create a jerry_value_t representing a SharedArrayBuffer object.

Note:

  • This API depends on a build option (JERRY_BUILTIN_SHAREDARRAYBUFFER).
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_shared_arraybuffer (jerry_length_t size);
  • size - size of the backing store allocated for the shared array buffer in bytes.
  • return value - the new SharedArrayBuffer as a jerry_value_t

New in version [[NEXT_RELEASE]].

Example

{
  jerry_value_t buffer_value = jerry_shared_arraybuffer (15);

  ... // use the SharedArrayBuffer

  jerry_value_free (buffer_value);
}

See also

jerry_shared_arraybuffer_external

Summary

Creates a jerry_value_t representing an SharedArrayBuffer object with user specified back-buffer.

User must pass a buffer pointer which is at least size big. After the object is not needed the GC will call the free_cb so the user can release the buffer which was provided.

Note:

  • This API depends on a build option (JERRY_BUILTIN_SHAREDARRAYBUFFER).
  • If buffer_p is NULL, the buffer is allocated by the allocator callback passed to jerry_arraybuffer_allocator
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_shared_arraybuffer_external (uint8_t *buffer_p,
                                   const jerry_length_t size,
                                   jerry_value_free_callback_t free_cb);
  • buffer_p - the backing store used by the shared array buffer object.
  • size - size of the buffer in bytes.
  • arraybuffer_user_p - user pointer assigned to the shared array buffer object.
  • return value
    • value of the newly constructed shared array buffer object.

New in version [[NEXT_RELEASE]].

Example

{
  uint8_t buffer_p[15];
  jerry_value_t buffer_value = jerry_shared_arraybuffer_external (buffer_p, 15, NULL);

  ... // use the shared array buffer

  jerry_value_free (buffer_value);
}

See also

jerry_boolean

Summary

Create a jerry_value_t representing a boolean value from the given boolean parameter.

Notes:

  • The boolean values (true/false) are fixed constants. Their values can be copied any number of times without calling jerry_value_copy, and freeing it with jerry_value_free is optional.

Prototype

jerry_value_t
jerry_boolean (bool value);
  • value - raw boolean value.
  • return value - a jerry_value_t created from the given boolean argument.

Example

{
  jerry_value_t boolean_value = jerry_boolean (true);

  ... // usage of the value

  jerry_value_free (boolean_value);
}

See also

jerry_error

Summary

Create new JavaScript Error object with the specified error message.

Important! The error_type argument must not be JERRY_ERROR_NONE. Creating an Error object with no error type is not valid.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_error (jerry_error_t error_type, jerry_value_t message);
  • error_type - type of error
  • message - error message string
  • return value - constructed error object

Example

{
  jerry_value_t message = jerry_string_sz ("error");
  jerry_value_t error_obj = jerry_error (JERRY_ERROR_COMMON, message);

  ... // usage of error_obj


  jerry_value_free (error_obj);
  jerry_value_free (message);
}

See also

jerry_error_sz

Summary

Create new JavaScript Error object, using the a zero-terminated string as the error message.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_error_sz (jerry_error_t error_type, const char *message_p);
  • error_type - type of the error
  • message_p - value of ‘message’ property of the constructed error object
  • return value - constructed error object

Example

{
  jerry_value_t error_obj = jerry_error_sz (JERRY_ERROR_TYPE, "error");

  ... // usage of error_obj

  jerry_value_free (error_obj);
}

See also

jerry_dataview

Summary

Create new JavaScript DataView object.

Note:

  • This API depends on a build option (JERRY_BUILTIN_DATAVIEW) and can be checked in runtime with the JERRY_FEATURE_DATAVIEW feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_dataview (const jerry_value_t array_buffer,
                const jerry_length_t byte_offset,
                const jerry_length_t byte_length)
  • array_buffer - arrayBuffer to create DataView from
  • byte_offset - offset in bytes, to the first byte in the buffer
  • byte_length - number of elements in the byte array
  • return value
    • value of the constructed DataView object - if success
    • exception - otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t arraybuffer = jerry_arraybuffer (16);
  jerry_value_t dataview = jerry_dataview (arraybuffer, 0, 16);

  // usage of dataview

  jerry_value_free (dataview);
  jerry_value_free (arraybuffer);

  jerry_cleanup ();
  return 0;
}

See also

jerry_function_external

Summary

Create an external function object.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_function_external (jerry_external_handler_t handler_p);
  • handler_p - pointer to native handler of the function object
  • return value - value of the constructed function object

Example

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static jerry_value_t
handler (const jerry_call_info_t *call_info_p,
         const jerry_value_t args_p[],
         const jerry_length_t args_cnt)
{
  printf ("Native handler called!\n");

  return jerry_boolean (true);
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t func_val = jerry_function_external (handler);
  jerry_value_t glob_obj = jerry_current_realm ();

  // after this, script can invoke the native handler through "handler_field (1, 2, 3);"
  jerry_value_t prop_name = jerry_string_sz ("handler_field");
  // set property and release the return value without any check
  jerry_value_free (jerry_object_set (glob_obj, prop_name, func_val));
  jerry_value_free (prop_name);

  jerry_value_free (func_val);
  jerry_value_free (glob_obj);

  // Test the method by calling it
  const char *test_src = "handler_field ();";
  jerry_value_t ret_val = jerry_eval ((const jerry_char_t *) test_src,
                                      strlen (test_src),
                                      JERRY_PARSE_NO_OPTS);
  // release the eval result
  jerry_value_free (ret_val);
  jerry_cleanup ();
  return 0;
}

See also

jerry_number

Summary

Creates a jerry_value_t representing a number value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_number (double value);
  • value - double value from which a jerry_value_t will be created
  • return value - a jerry_value_t created from the given double argument

Example

{
  jerry_value_t number_value = jerry_number (3.14);

  ... // usage of the value

  jerry_value_free (number_value);
}

See also

jerry_infinity

Summary

Creates a jerry_value_t representing a positive or negative infinity value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_infinity (bool sign);
  • sign - true for negative Infinity and false for positive Infinity
  • return value - a jerry_value_t representing the infinity value

Example

{
  jerry_value_t positive_inf_value = jerry_infinity (false);

  ... // usage of the positive_inf_value

  jerry_value_free (positive_inf_value);
}

See also

jerry_nan

Summary

Creates a jerry_value_t representing a not-a-number value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_nan (void);
  • return value - a jerry_value_t representing the not-a-number value

Example

{
  jerry_value_t nan_value = jerry_nan ();

  ... // usage of the nan_value

  jerry_value_free (nan_value);
}

See also

jerry_null

Summary

Creates and returns a jerry_value_t with type null object.

Notes:

  • The null value is a fixed constant. Its value can be copied any number of times without calling jerry_value_copy, and freeing it with jerry_value_free is optional.

Prototype

jerry_value_t
jerry_null (void);
  • return value - a jerry_value_t representing null.

Example

{
  jerry_value_t null_value = jerry_null ();

  ... // usage of the value

  jerry_value_free (null_value);
}

See also

jerry_object

Summary

Create new JavaScript object, like with new Object().

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object (void);
  • return value - value of the created object

Example

{
  jerry_value_t object_value = jerry_object ();

  ... // usage of object_value

  jerry_value_free (object_value);
}

See also

jerry_promise

Summary

Create an empty promise object which can be resolved or rejected later by calling jerry_promise_resolve or jerry_promise_reject.

Note:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_promise (void)
  • return value - value of the newly created promise

New in version 2.0.

Example

{
  jerry_value_t p = jerry_promise ();

  ...// usage of the promise

  jerry_value_free (p);
}

See also

jerry_proxy

Summary

Create a new Proxy object with the given target and handler.

Note:

  • This API depends on a build option (JERRY_BUILTIN_PROXY) and can be checked in runtime with the JERRY_FEATURE_PROXY feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_proxy (const jerry_value_t target, const jerry_value_t handler);
  • target - proxy target
  • handler - proxy handler
  • return exception - if the Proxy construction fails value of the newly created proxy object - otherwise

New in version 2.3.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t target = jerry_object ();
  jerry_value_t handler = jerry_object ();
  jerry_value_t proxy = jerry_proxy (target, handler);

  jerry_value_free (target);
  jerry_value_free (handler);

  // usage of the proxy

  jerry_value_free (proxy);

  jerry_cleanup ();
}

See also

jerry_proxy_custom

Summary

Create a new Proxy object with the given target and handler. The behaviour of the Proxy can be specialized with an options argument.

Note:

  • This API depends on a build option (JERRY_BUILTIN_PROXY) and can be checked in runtime with the JERRY_FEATURE_PROXY feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_proxy_custom (const jerry_value_t target,
                    const jerry_value_t handler,
                    uint32_t options);
  • target - proxy target
  • handler - proxy handler
  • options - any combination of jerry_proxy_custom_behavior_t options
  • return thrown exception - if the Proxy construction fails value of the newly created proxy object - otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t target = jerry_object ();
  jerry_value_t handler = jerry_object ();
  jerry_value_t proxy = jerry_proxy_custom (target, handler, JERRY_PROXY_SKIP_RESULT_VALIDATION);

  jerry_value_free (target);
  jerry_value_free (handler);

  // usage of the proxy

  jerry_value_free (proxy);

  jerry_cleanup ();
}

See also

jerry_string_sz

Summary

Create string from a zero-terminated ASCII string.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_string_sz (const char *str_p);
  • str_p - non-null pointer to string
  • return value - created string

Example

{
  const char char_array[] = "a string";
  jerry_value_t string_value = jerry_string_sz (char_array);

  ... // usage of string_value

  jerry_value_free (string_value);
}

See also

jerry_string

Summary

Create a string from a buffer using the specified encoding. The data in the buffer must be valid for the encoding.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_string (const jerry_char_t *buffer_p,
              jerry_size_t buf_size,
              jerry_encoding_t encoding)
  • buffer_p - non-null pointer to buffer
  • buf_size - size of the buffer
  • encoding - encoding of the string data
  • return value - value of the created string

Example

{
  const jerry_char_t char_array[] = "a string";
  jerry_value_t string_value = jerry_string (char_array,
                                             sizeof (char_array) - 1,
                                             JERRY_ENCODING_CESU8);

  ... // usage of string_value

  jerry_value_free (string_value);
}

See also

jerry_string_external_sz

Summary

Create an external string from a zero-terminated ASCII string. The string buffer passed to the function should not be modified until the free callback is called. This function can be used to avoid the duplication of large strings.

Note:

Prototype

jerry_value_t
jerry_string_external_sz (const char *str_p, void *user_p);
  • str_p - non-null pointer to string
  • user_p - user pointer passed to the callback when the string is freed
  • return value - value of the created string

New in version 2.4.

Changed in version [[NEXT_RELEASE]]: free_cb is replaced by user_p.

Example

{
  const char* string_p = "a large and immutable string: this is a story about ....";
  jerry_value_t string_value = jerry_string_external_sz (string_p, NULL);

  ... // usage of string_value

  jerry_value_free (string_value);
}

See also

jerry_string_external

Summary

Create an external string from a valid CESU8 string. The string buffer passed to the function should not be modified until the free callback is called. This function can be used to avoid the duplication of large strings.

Note:

Prototype

jerry_value_t
jerry_string_external (const jerry_char_t *str_p,
                       jerry_size_t str_size,
                       void *user_p);
  • str_p - non-null pointer to string
  • str_size - size of the string
  • user_p - user pointer passed to the callback when the string is freed
  • return value - value of the created string

New in version 2.4.

Changed in version [[NEXT_RELEASE]]: free_cb is replaced by user_p.

Example

{
  const char* string_p = "a large and immutable string: this is a story about ....";
  jerry_value_t string_value = jerry_string_external ((const jerry_char_t *) string_p,
                                                      strlen (string_p),
                                                      NULL);

  ... // usage of string_value

  jerry_value_free (string_value);
}

See also

jerry_symbol

Summary

Create symbol from an API value.

Note:

  • The given argument is converted to string. This operation can throw an exception.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_symbol_with_description (const jerry_value_t value)
  • value - API value
  • return value
    • value of the created symbol, if success
    • thrown exception, otherwise

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t string_value = jerry_string_sz ("Symbol description string");
  jerry_value_t symbol_value = jerry_symbol_with_description (string_value);

  // The description value is no longer needed
  jerry_value_free (string_value);

  // usage of symbol_value

  jerry_value_free (symbol_value);

  jerry_cleanup ();
}

See also

jerry_bigint

Summary

Create BigInt value from uint64 digits

Note:

  • This API depends on a build option (JERRY_BUILTIN_BIGINT) and can be checked in runtime with the JERRY_FEATURE_BIGINT feature enum value, see: jerry_feature_enabled.
  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_bigint (const uint64_t *digits_p, uint32_t size, bool sign)
  • digits_p - array of uint64 digits, least significant digit first
  • size - size of the digits_p array
  • sign - false if the created value should be positive, and true if the created value should be negative
  • return value
    • value of the created bigint, if success
    • thrown exception, otherwise

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  uint64_t digits[2] = { 0x1, 0x1 };
  jerry_value_t bigint_value = jerry_bigint (digits, 2, true);

  // usage of bigint_value

  jerry_value_free (bigint_value);

  jerry_cleanup ();
}

See also

jerry_regexp_sz

Summary

Returns a RegExp object created from the argument ASCII string pattern, or an exception if the construction of the object fails. Optional flags can be set using jerry_regexp_flags_t. These flags can be combined together with the binary OR operator or used on their own as enum values.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_regexp_sz (const jerry_char_t *pattern_p, uint16_t flags);
  • pattern_p - the RegExp pattern as a zero-terminated UTF-8 string
  • flags - optional flags for the RegExp object, see jerry_regexp_flags_t
  • return value - the RegExp object as a jerry_value_t

New in version 2.0.

Example

{
  jerry_char_t pattern_p = "[cgt]gggtaaa|tttaccc[acg]";
  uint16_t pattern_flags = JERRY_REGEXP_FLAG_IGNORE_CASE;

  jerry_value_t regexp = jerry_regexp_sz (pattern_p, pattern_flags);

  ...

  jerry_value_free (regexp);
}

jerry_regexp

Summary

Returns a RegExp object from the argument pattern, or an exception if the construction of the object fails. Optional flags can be set using jerry_regexp_flags_t. These flags can be combined together with the binary OR operator or used on their own as enum values.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_regexp (const jerry_value_t pattern, uint16_t flags);
  • pattern_p - the RegExp pattern as a zero-terminated UTF-8 string
  • pattern_size - size of the pattern
  • flags - optional flags for the RegExp object, see jerry_regexp_flags_t
  • return value - the RegExp object as a jerry_value_t

New in version 2.0.

Example

{
  jerry_char_t pattern_p = "[cgt]gggtaaa|tttaccc[acg]";
  jerry_size_t pattern_size = sizeof (pattern_p) - 1;
  jerry_value_t pattern_str = jerry_string (pattern_p, pattern_size, JERRY_ENCODING_UTF8);

  uint16_t pattern_flags = JERRY_REGEXP_FLAG_IGNORE_CASE;

  jerry_value_t regexp = jerry_regexp (pattern_str, pattern_flags);
  jerry_value_free (pattern_str);

  ...

  jerry_value_free (regexp);
}

jerry_typedarray

Summary

Create a jerry_value_t representing an TypedArray object.

For the new object the type of the TypedArray (see: jerry_typedarray_type_t) and element count can be specified.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_typedarray (jerry_typedarray_type_t type_name, jerry_length_t item_count);
  • type_name - type of TypedArray to create
  • item_count - number of items in the new TypedArray
  • return value - the new TypedArray as a jerry_value_t

New in version 2.0.

Example

{
  jerry_value_t array = jerry_typedarray (JERRY_TYPEDARRAY_UINT16, 15);

  ... // use the TypedArray

  jerry_value_free (array);
}

See also

jerry_typedarray_with_buffer

Summary

Create a jerry_value_t representing an TypedArray object using an already existing ArrayBuffer object.

For the new object the type of the TypedArray (see: jerry_typedarray_type_t) and element count can be specified.

The developer must ensure that the ArrayBuffer has the correct length for the given type of TypedArray otherwise an exception is generated.

The JavaScript equivalent of this function is: new %TypedArray%(arraybuffer) where %TypedArray% is one of the allowed TypedArray functions.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_typedarray_with_buffer (jerry_typedarray_type_t type_name,
                              const jerry_value_t arraybuffer);
  • type_name - type of TypedArray to create
  • arraybuffer - the ArrayBuffer to use for the new TypedArray
  • return value
    • the new TypedArray as a jerry_value_t
    • exception if the ArrayBuffer does not have enough space for the given type of TypedArray

New in version 2.0.

Example

{
  jerry_value_t buffer = jerry_array_buffer (12 * 2);
  jerry_value_t array = jerry_typedarray_with_buffer (JERRY_TYPEDARRAY_UINT16, buffer);
  jerry_value_free (buffer);

  ... // use the TypedArray

  jerry_value_free (array);
}

See also

jerry_typedarray_with_buffer_span

Summary

Create a jerry_value_t representing an TypedArray object using an already existing ArrayBuffer object and by specifying the byteOffset, and length properties.

For the new object the type of the TypedArray (see: jerry_typedarray_type_t) and element count can be specified.

The developer must ensure that the ArrayBuffer has the correct length for the given type of TypedArray otherwise an exception is generated.

The JavaScript equivalent of this function is: new %TypedArray%(arraybuffer, byteOffset, length) where %TypedArray% is one of the allowed TypedArray functions.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_typedarray_with_buffer_span (jerry_typedarray_type_t type_name,
                                   const jerry_value_t arraybuffer,
                                   jerry_length_t byte_offset,
                                   jerry_length_t length);
  • type_name - type of TypedArray to create
  • arraybuffer - the ArrayBuffer to use for the new TypedArray
  • byte_offset - start offset to use for the ArrayBuffer
  • length - number of elements to used from the ArrayBuffer (this is not the same as the byteLength)
  • return value
    • the new TypedArray as a jerry_value_t
    • exception if the ArrayBuffer does not have enough space for the given type of TypedArray

New in version 2.0.

Example

{
  jerry_value_t buffer = jerry_array_buffer (12 * 2);
  jerry_value_t array = jerry_typedarray_with_buffer_span (JERRY_TYPEDARRAY_UINT16, buffer, 4, 10);
  jerry_value_free (buffer);

  ... // use the TypedArray

  jerry_value_free (array);
}

See also

jerry_container

Summary

Create a jerry_value_t representing a given type container object.

Notes:

  • This method is expected to work the same way as the JavaScript Map constructor.
  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_BUILTIN_CONTAINER) and can be checked in runtime with the JERRY_FEATURE_MAP, JERRY_FEATURE_SET, JERRY_FEATURE_WEAKMAP, JERRY_FEATURE_WEAKSET feature enum values. see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_container (jerry_container_type_t container_type,
                 const jerry_value_t *arguments_list_p,
                 jerry_length_t arguments_list_len);
  • container_type - Type of the container to be created, see jerry_container_type_t.
  • arguments_list_p - The arguments passed to the container constructor to be inserted to the container.
  • arguments_list_len - The length of the above arguments.
  • return value - the new container object as a jerry_value_t

New in version 2.3.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);
  jerry_char_t src[] = "[1,2,3,4].entries()";
  jerry_value_t iterable = jerry_eval (src, sizeof (src) - 1, JERRY_PARSE_NO_OPTS);

  jerry_value_t map = jerry_container (JERRY_CONTAINER_TYPE_MAP, &iterable, 1);
  jerry_value_free (iterable);

  // use the Map

  jerry_value_free (map);

  jerry_cleanup ();
  return 0;
}

See also

jerry_undefined

Summary

Creates a jerry_value_t representing an undefined value.

Notes:

  • The undefined value is a fixed constant. Its value can be copied any number of times without calling jerry_value_copy, and freeing it with jerry_value_free is optional.

Prototype

jerry_value_t
jerry_undefined (void);
  • return value - value of undefined

Example

{
  jerry_value_t undefined_value = jerry_undefined ();

  ... // usage of the value

  jerry_value_free (undefined_value);
}

See also

jerry_realm

Summary

Creates a jerry_value_t representing a new global object.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_BUILTIN_REALMS) and can be checked in runtime with the JERRY_FEATURE_REALM feature enum value. see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_realm (void);
  • return value - realm object value

New in version 2.4.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t realm_value = jerry_realm ();

  // usage of the value

  jerry_value_free (realm_value);
  jerry_cleanup ();

  return 0;
}

See also

General API functions of JS objects

jerry_object_has

Summary

Checks whether the object or its prototype objects have the given property.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_has (const jerry_value_t obj_val,
                  const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value - JavaScript value that evaluates to
    • exception - if the operation fail
    • true/false API value - depend on whether the property exists

Changed in version 2.0: The return value type is now a JavaScript value and not a primitive boolean value.

Changed in version 2.3: The return value can be an exception value.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("handler_field");

  jerry_value_t has_prop_js = jerry_object_has (global_object, prop_name);
  bool has_prop = jerry_value_is_true (has_prop_js);

  jerry_value_free (has_prop_js);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  jerry_cleanup ();

  return 0;
}

See also

jerry_object_has_own

Summary

Checks whether the object has the given property.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_has_own (const jerry_value_t obj_val,
                      const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value - JavaScript value that evaluates to
    • exception - if the operation fails
    • true/false API value - depend on whether the property exists

Changed in version 2.0: The return value type is now a JavaScript value and not a primitive boolean value.

Changed in version 2.3: The return value can be an exception value.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("handler_field");

  jerry_value_t has_prop_js = jerry_object_has_own (global_object, prop_name);
  bool has_prop = jerry_value_is_true (has_prop_js);

  jerry_value_free (has_prop_js);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  jerry_cleanup ();

  return 0;
}

See also

jerry_object_has_internal

Summary

Checks whether the object has the given internal property.

Note:

Prototype

bool
jerry_object_has_internal (const jerry_value_t obj_val,
                           const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value
    • true, if the property exists
    • false, otherwise

New in version 2.2.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("hidden_property");

  bool has_internal_js_prop = jerry_object_has_internal (global_object, prop_name);

  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  return 0;
}

See also

jerry_object_delete

Summary

Delete a property from an object.

Prototype

jerry_value_t
jerry_object_delete (const jerry_value_t obj_val,
                     const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value
    • true, if property was deleted successfully
    • exception, otherwise

Example

{
  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("my_prop");

  jerry_value_t delete_result = jerry_object_delete (global_object, prop_name);
  /* use "delete_result" */

  jerry_value_free (delete_result);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);
}

See also

jerry_object_delete_index

Summary

Delete indexed property from the specified object.

Prototype

jerry_value_t
jerry_object_delete_index (const jerry_value_t obj_val,
                           uint32_t index);
  • obj_val - object value
  • index - index number
  • return value
    • true value, if property was deleted successfully
    • exception, otherwise

New in version 2.0.

Example

{
  jerry_value_t object;

  ... // create or copy object

  jerry_value_t delete_result = jerry_object_delete_index (object, 5);

  jerry_value_free (delete_result);
  jerry_value_free (object);
}

See also

jerry_object_delete_internal

Summary

Delete an internal property from an object.

Note: Properties which were not created with jerry_object_set_internal are excluded during the operation.

Prototype

bool
jerry_object_delete_internal (const jerry_value_t obj_val,
                              const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value
    • true, if property was deleted successfully
    • false, otherwise

New in version 2.2.

Example

{
  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("hidden_property");

  bool delete_result = jerry_object_delete_internal (global_object, prop_name);
  /* use "delete_result" */

  jerry_value_free (prop_name);
  jerry_value_free (global_object);
}

See also

jerry_object_get

Summary

Get value of a property to the specified object with the given name.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_get (const jerry_value_t obj_val,
                  const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value
    • value of property, if success
    • thrown exception, otherwise

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("Object");

  jerry_value_t prop_value = jerry_object_get (global_object, prop_name);

  /* use "prop_value" then release it. */

  jerry_value_free (prop_value);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  return 0;
}

See also

jerry_object_get_index

Summary

Get value by an index from the specified object.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_get_index (const jerry_value_t obj_val,
                        uint32_t index);
  • obj_val - object value
  • index - index number
  • return value
    • stored value on the specified index, if success
    • thrown exception, otherwise.

Example

{
  jerry_value_t object;

  ... // create or copy object

  jerry_value_t value = jerry_object_get_index (object, 5);

  ...

  jerry_value_free (value);
  jerry_value_free (object);
}

See also

jerry_object_find_own

Summary

Get the own property value of an object with the given name. The function tells whether the property is found, and the receiver object can be specified as well. The receiver is passed as the this argument for getters, and the receiver argument for Proxy get traps.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • The found_p argument is ignored if its value is NULL.
  • The target value of found_p argument is set to false when the arguments are invalid, e.g. obj_val is not an object.

Prototype

jerry_value_t
jerry_object_find_own (const jerry_value_t obj_val,
                       const jerry_value_t prop_name_val,
                       const jerry_value_t receiver_val,
                       bool *found_p);
  • obj_val - object value
  • prop_name_val - property name
  • receiver_val - receiver object
  • found_p - [out] true, if the property is found or obj_val is a Proxy object, false otherwise
  • return value
    • value of property, if success
    • thrown exception, otherwise

Example

#include "jerryscript.h"
#include "stdio.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("Object");

  bool found;
  jerry_value_t prop_value = jerry_object_find_own (global_object, prop_name, global_object, &found);

  if (found)
  {
    printf ("Property is found!\n");
  }

  /* use "prop_value" then release it. */

  jerry_value_free (prop_value);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  return 0;
}

See also

jerry_object_get_internal

Summary

Get value of an internal property to the specified object with the given name.

Note:

Prototype

jerry_value_t
jerry_object_get_internal (const jerry_value_t obj_val,
                           const jerry_value_t prop_name_val);
  • obj_val - object value
  • prop_name_val - property name
  • return value
    • value of property, if the internal property exists
    • undefined value, if the, if the internal does not property exists
    • thrown exception, otherwise

New in version 2.2.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("hidden_property");

  jerry_value_t prop_value = jerry_object_get_internal (global_object, prop_name);

  /* use "prop_value" then release it. */

  jerry_value_free (prop_value);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  return 0;
}

See also

jerry_object_set

Summary

Set a property to the specified object with the given name.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_set (const jerry_value_t obj_val,
                  const jerry_value_t prop_name_val,
                  const jerry_value_t value_to_set)
  • obj_val - object value
  • prop_name_val - property name
  • value_to_set - value to set
  • return value
    • true, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t value_to_set;

  ... // create or copy value to set

  jerry_value_t glob_obj = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("my_prop");

  jerry_value_t set_result = jerry_object_set (glob_obj, prop_name, value_to_set);

  ... // check result of property set call

  jerry_value_free (set_result);
  jerry_value_free (prop_name);

  ...

  jerry_value_free (value_to_set);
  jerry_value_free (glob_obj);
}

See also

jerry_object_set_index

Summary

Set indexed value in the specified object

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_set_index (const jerry_value_t obj_val,
                        uint32_t index,
                        const jerry_value_t value_to_set);
  • obj_val - object value
  • index - index number
  • value_to_set - value to set
  • return value
    • true, if field value was set successfully
    • thrown exception, otherwise

Example

{
  jerry_value_t object;
  jerry_value_t value_to_set;

  ... // create or copy object and value to set

  jerry_value_t ret_val = jerry_object_set_index (object, 5, value_to_set);

  ...

  jerry_value_free (value_to_set);
  jerry_value_free (ret_val);
  jerry_value_free (object);
}

See also

jerry_object_set_internal

Summary

Set an internal property to the specified object with the given name.

Note:

  • The property cannot be accessed from the JavaScript context, only from the public API.
  • It is different from jerry_object_set_native_ptr in that any jerry API value can be hidden from the JavaScript context, not only native pointers.

Prototype

bool
jerry_object_set_internal (const jerry_value_t obj_val,
                           const jerry_value_t prop_name_val,
                           const jerry_value_t value_to_set)
  • obj_val - object value
  • prop_name_val - property name
  • value_to_set - value to set
  • return value
    • true, if success
    • thrown exception, otherwise

New in version 2.2.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t prop_name = jerry_string_sz ("hidden_property");
  jerry_value_t value_to_set = jerry_number (5);

  bool set_result = jerry_object_set_internal (global_object, prop_name, value_to_set);

  /* check the result of internal property set call */

  jerry_value_free (value_to_set);
  jerry_value_free (prop_name);
  jerry_value_free (global_object);

  return 0;
}

See also

jerry_property_descriptor

Summary

Create a property descriptor and initialize it with default values. This means that all fields in the jerry_property_descriptor_t struct will be set to zero or false depending on the field’s type.

Prototype

jerry_property_descriptor_t
jerry_property_descriptor (void);

New in version [[NEXT_RELEASE]]: Replaces jerry_init_property_descriptor_fields.

Example

{
  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  ... // usage of prop_desc

  jerry_property_descriptor_free (&prop_desc);
}

For a more complete example see jerry_object_define_own_prop.

See also

jerry_object_define_own_prop

Summary

Define a property to the specified object with the given name.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_define_own_prop (const jerry_value_t obj_val,
                              const jerry_value_t prop_name_val,
                              const jerry_property_descriptor_t *prop_desc_p);
  • obj_val - target object where the property should be registered
  • prop_name_val - property name
  • prop_desc_p - pointer to property descriptor
  • return value
    • true, if success
    • thrown exception, otherwise

Example

Registering a simple value property via the jerry_object_define_own_prop method:

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_obj_val = jerry_current_realm ();

  // configure the property
  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  // create or copy value to set
  // For example:
  jerry_value_t value_to_set = jerry_number (33);

  // set the property descriptor fields:
  // set the "JERRY_PROP_IS_VALUE_DEFINED" flag to indicate the "value"
  //  field should be used during the property registration.
  // set the writable, configurable, enumerable flags to true
  prop_desc.flags |= (JERRY_PROP_IS_WRITABLE_DEFINED
                      | JERRY_PROP_IS_WRITABLE
                      | JERRY_PROP_IS_CONFIGURABLE_DEFINED
                      | JERRY_PROP_IS_CONFIGURABLE
                      | JERRY_PROP_IS_ENUMERABLE_DEFINED
                      | JERRY_PROP_IS_ENUMERABLE
                      | JERRY_PROP_IS_VALUE_DEFINED);

  // set the "value" field to the number 33
  prop_desc.value = value_to_set;

  // add the property as "my_prop" for the global object
  jerry_value_t prop_name = jerry_string_sz ("my_prop");
  jerry_value_t return_value = jerry_object_define_own_prop (global_obj_val, prop_name, &prop_desc);
  if (jerry_value_is_exception (return_value))
  {
    // there was an error
  }

  // re-define the property with the enumerable flag set to false
  prop_desc.flags &= (uint16_t) ~JERRY_PROP_IS_ENUMERABLE;
  return_value = jerry_object_define_own_prop (global_obj_val, prop_name, &prop_desc);
  if (jerry_value_is_exception (return_value))
  {
    // there was an error
  }

  // if there was no exception at this point the global object should have a "my_prop" property

  jerry_value_free (return_value);
  jerry_value_free (prop_name);

  jerry_property_descriptor_free (&prop_desc);
  jerry_value_free (global_obj_val);

  jerry_cleanup ();
  return 0;
}

Registering a getter/setter property via the jerry_object_define_own_prop method:

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static int counter = 0;

static jerry_value_t
method_getter (const jerry_call_info_t *call_info_p,
               const jerry_value_t args[],
               const jerry_length_t argc)
{
  counter++;
  printf("Getter called, returning: %d\n", counter);

  return jerry_number (counter);
}

static jerry_value_t
method_setter (const jerry_call_info_t *call_info_p,
               const jerry_value_t args[],
               const jerry_length_t argc)
{
  // Note: the arguments count and type should be checked
  // in this example it is omitted!

  double new_value = jerry_value_as_number (args[0]);
  counter = (int) new_value;

  printf("Setter called, setting: %d\n", counter);

  return jerry_undefined ();
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global_obj_val = jerry_current_realm ();

  // configure the property
  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  // set the property descriptor fields:

  prop_desc.flags |= JERRY_PROP_IS_GET_DEFINED | JERRY_PROP_IS_SET_DEFINED;
  prop_desc.getter = jerry_function_external (method_getter);
  prop_desc.setter = jerry_function_external (method_setter);

  // add the property as "my_prop" for the global object
  jerry_value_t prop_name = jerry_string_sz ("my_prop");
  jerry_value_t return_value = jerry_object_define_own_prop (global_obj_val, prop_name, &prop_desc);
  if (jerry_value_is_exception (return_value))
  {
    // there was an error
  }

  // if there was no exception at this point the global object should have a "my_prop" property

  jerry_value_free (return_value);
  jerry_value_free (prop_name);

  jerry_property_descriptor_free (&prop_desc);
  jerry_value_free (global_obj_val);

  // run an example js code to use the getter/setters

  const char *src_p = "this.my_prop; this.my_prop; this.my_prop = 4; this.my_prop";
  jerry_value_t eval_result = jerry_eval ((const jerry_char_t *) src_p, strlen (src_p), JERRY_PARSE_NO_OPTS);

  // "eval_result" is the last result of "this.my_prop" that is "5" currently.
  double result_number = jerry_value_as_number (eval_result);
  printf("output: %lf\n", result_number);

  jerry_cleanup ();

  return result_number != 5.0;
}

See also

jerry_object_get_own_prop

Summary

Construct property descriptor from specified property.

Prototype

jerry_value_t
jerry_object_get_own_prop (const jerry_value_t obj_val,
                           const jerry_value_t prop_name_val,
                           jerry_property_descriptor_t *prop_desc_p);
  • obj_val - object value
  • prop_name_val - property name
  • prop_desc_p - pointer to property descriptor
  • return value

Changed in version [[NEXT_RELEASE]]: Return value type is changed to jerry_value_t.

Example

{
  jerry_value_t global_obj_val = jerry_current_realm ();

  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  jerry_value_t prop_name = jerry_string_sz ("my_prop");
  jerry_object_get_own_prop (global_obj_val, prop_name, &prop_desc);
  jerry_value_free (prop_name);

  ... // usage of property descriptor

  jerry_property_descriptor_free (&prop_desc);
  jerry_value_free (global_obj_val);
}

See also

jerry_property_descriptor_free

Summary

Free fields of property descriptor (setter, getter and value).

Prototype

void
jerry_property_descriptor_free (const jerry_property_descriptor_t *prop_desc_p);
  • prop_desc_p - pointer to property descriptor

New in version [[NEXT_RELEASE]]: Replaces jerry_free_property_descriptor_fields.

Example

{
  jerry_property_descriptor_t prop_desc = jerry_property_descriptor ();

  ... // usage of property descriptor

  jerry_property_descriptor_free (&prop_desc);
}

See also

jerry_call

Summary

Call function specified by a function value. The argument values must not be exceptions. Value of this parameter should be set to undefined for non-method calls.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_call (const jerry_value_t func_obj_val,
            const jerry_value_t this_val,
            const jerry_value_t args_p[],
            jerry_size_t args_count);
  • func_obj_val - the function object to call
  • this_val - object for ‘this’ binding
  • args_p - function’s call arguments
  • args_count - number of arguments
  • return value - returned jerry value of the called function

Example

{
  jerry_value_t target_function;

  ... // create or get "target_function"

  if (jerry_value_is_function (target_function))
  {
    jerry_value_t this_val = jerry_undefined ();
    jerry_value_t ret_val = jerry_call (target_function, this_val, NULL, 0);

    if (!jerry_value_is_exception (ret_val))
    {
      ... // handle return value
    }

    jerry_value_free (ret_val);
    jerry_value_free (this_val);
  }

  jerry_value_free (target_function);
}

See also

jerry_construct

Summary

Construct object, invoking specified function object as constructor. Error flag must not be set for any arguments of this function.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_construct (const jerry_value_t func_obj_val,
                 const jerry_value_t args_p[],
                 jerry_size_t args_count);
  • func_obj_val - function object to call
  • args_p - function’s call arguments
  • args_count - number of arguments
  • return value - returned value of the invoked constructor

Example

{
  jerry_value_t val;

  ... // receiving val

  if (jerry_is_constructor (val))
  {
    jerry_value_t ret_val = jerry_construct (val, NULL, 0);

    if (!jerry_value_is_exception (ret_val))
    {
      ... // handle return value
    }

    jerry_value_free (ret_val);
  }
}

See also

jerry_object_keys

Summary

Get keys of the specified object value.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_keys (const jerry_value_t obj_val);
  • obj_val - object value
  • return value
    • array object value, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t object;
  ... // create or copy object

  jerry_value_t keys_array = jerry_object_keys (object);

  ... // usage of keys_array

  jerry_value_free (keys_array);
}

See also

jerry_object_proto

Summary

Get the prototype of the specified object.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_proto (const jerry_value_t obj_val);
  • obj_val - object value
  • return value
    • object value, if success
    • null or thrown exception, otherwise

Example

{
  jerry_value_t object;
  ... // create or copy object

  jerry_value_t prototype = jerry_object_proto (object);

  ... // usage of prototype object

  jerry_value_free (prototype);
  jerry_value_free (object);
}

See also

jerry_object_set_proto

Summary

Set the prototype of the specified object.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_object_set_proto (const jerry_value_t obj_val,
                        const jerry_value_t proto_obj_val);
  • obj_val - object value
  • proto_obj_val - prototype object value
  • return value
    • true, if success
    • thrown exception, otherwise

Example

{
  jerry_value_t object;
  jerry_value_t prototype;

  ... // create or copy object and prototype

  jerry_value_t ret_val = jerry_object_set_proto (object, prototype);

  jerry_value_free (ret_val);
  jerry_value_free (prototype);
  jerry_value_free (object);
}

See also

jerry_object_get_native_ptr

Summary

Get native pointer by the given type information. The pointer and the type information are previously associated with the object by jerry_object_set_native_ptr.

Note: native_info_p can be NULL

Prototype

void *
jerry_object_get_native_ptr (const jerry_value_t object,
                             const jerry_object_native_info_t *native_info_p)
  • object - object value to get native pointer from.
  • native_info_p - native pointer’s type information.
  • return value
    • native pointer associated with the argument object for the given native type info

New in version 2.0: Changed from jerry_get_object_native_handle.

Example

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jerryscript.h"

typedef struct
{
  char *data_p;
  unsigned int length;
} buffer_native_object_t;

typedef struct
{
  int area;
  int perimeter;
} shape_native_object_t;

#define SECRET_INFO ((void *) 42)

static void
buffer_native_freecb (void *native_p,
                      jerry_object_native_info_t *info_p)
{
  (void) info_p;

  char *data_p = ((buffer_native_object_t*)native_p)->data_p;

  if (data_p != NULL)
  {
    free (data_p);
  }

  free (native_p);
}

static void
shape_native_freecb (void *native_p,
                     jerry_object_native_info_t *info_p)
{
  (void) info_p;

  free (native_p);
}

static void
destructor_freecb (void *native_p,
                   jerry_object_native_info_t *info_p)
{
  (void) native_p;
  (void) info_p;

   printf("Note: the object has been freed\n");
}

// NOTE: The address (!) of type_info acts as a way to uniquely "identify" the
// C type `buffer_native_object_t *`.
static const jerry_object_native_info_t buffer_obj_type_info =
{
  .free_cb = buffer_native_freecb
};

// NOTE: The address (!) of type_info acts as a way to uniquely "identify" the
// C type `shape_native_object_t *`.
static const jerry_object_native_info_t shape_obj_type_info =
{
  .free_cb = shape_native_freecb
};

// NOTE: The address (!) of type_info is the unique "identifier"
static const jerry_object_native_info_t destructor_obj_type_info =
{
  .free_cb = destructor_freecb
};

static void
print_buffer (char *data_p,
              unsigned int length)
{
  for (unsigned int i = 0; i < length; ++i)
  {
    printf("%c", data_p[i]);
  }

  printf("\n");
}

static void
do_stuff (jerry_value_t object)
{
  void *native_p = jerry_object_get_native_ptr (object, &buffer_obj_type_info);

  if (native_p == NULL)
  {
    // Process the error
    return;
  }

  // It is safe to cast to buffer_native_object_t * and dereference the pointer:
  buffer_native_object_t *buffer_p = (buffer_native_object_t *) native_p;
  print_buffer (buffer_p->data_p, buffer_p->length); // Usage of buffer_p

  bool need_shape_info = true; // implementation dependent

  if (need_shape_info)
  {
    native_p = jerry_object_get_native_ptr (object, &shape_obj_type_info);

    if (native_p == NULL)
    {
      // Process the error
      return;
    }

    // It is safe to cast to shape_native_object_t * and dereference the pointer:
    shape_native_object_t *shape_p = (shape_native_object_t *) native_p;

    printf("Area: %d\tPerimeter: %d\n", shape_p->area, shape_p->perimeter); // Usage of shape_p
  }

  bool need_secret_info = true; // implementation dependent

  if (need_secret_info)
  {
    native_p = jerry_object_get_native_ptr (object, NULL);

    if (native_p == NULL)
    {
      // Process the error
      return;
    }

    printf("Secret: %d\n", (int)((uintptr_t) native_p)); // Usage of native_p

    bool deleted = jerry_object_delete_native_ptr (object, NULL);

    if (deleted)
    {
      printf("The secret is no longer available\n");
    }
  }
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t object = jerry_object ();
  buffer_native_object_t *buffer_p = (buffer_native_object_t *) malloc (sizeof (buffer_native_object_t));
  buffer_p->length = 14;
  buffer_p->data_p = (char *) malloc (buffer_p->length * sizeof (char));
  memcpy (buffer_p->data_p, "My buffer data", buffer_p->length);
  jerry_object_set_native_ptr (object, &buffer_obj_type_info, buffer_p);

  shape_native_object_t *shape_p = (shape_native_object_t *) malloc (sizeof (shape_native_object_t));
  shape_p->area = 6;
  shape_p->perimeter = 12;
  jerry_object_set_native_ptr (object, &shape_obj_type_info, shape_p);

  // The native pointer can be NULL. This gives possibly to get notified via the native type info's
  // free callback when the object has been freed by the GC.
  jerry_object_set_native_ptr (object, &destructor_obj_type_info, NULL);

  // The native type info can be NULL as well. In this case the registered property is simply freed
  // when the object is freed by the GC.
  jerry_object_set_native_ptr (object, NULL, SECRET_INFO);

  do_stuff (object);

  jerry_value_free (object);
  jerry_cleanup ();

  return 0;
}

See also

jerry_object_set_native_ptr

Summary

Set native pointer and an optional type information for the specified object. You can get them by calling jerry_object_get_native_ptr later.

Notes:

  • If a native pointer was already set for the object with the same type information, its value is updated.
  • If a non-NULL free callback is specified in the native type information, it will be called by the garbage collector when the object is freed.
  • If the object is only referenced via the “global” object (or one of it’s “child”), the free callback will be invoked during the execution of jerry_cleanup.
  • The free callback can invoke API functions.

Note: If possible do not store API values in native pointers, rather check jerry_object_set_internal.

Prototype

void
jerry_object_set_native_ptr (const jerry_value_t obj_val,
                             const jerry_object_native_info_t *info_p,
                             void *native_p);
  • obj_val - object to set native pointer in.
  • info_p - native pointer’s type information or NULL. When used, this should be a long-lived pointer, usually a pointer to a static const jerry_object_native_info_t makes most sense.
  • native_p - native pointer.

New in version 2.0: Changed from jerry_set_object_native_handle.

Example

See jerry_object_get_native_ptr for a best-practice example.

See also

jerry_object_delete_native_ptr

Summary

Delete the native pointer of the specified object associated with the given native type info.

Notes:

  • If the specified object has no matching native pointer for the given native type info the operation has no effect.
  • The method does not invoke the free callback specified in the type info. If the native pointer should be freed then one must get the native pointer first and invoke the free callback manually before calling this method.
  • This operation cannot throw an exception.

Prototype

bool
jerry_object_delete_native_ptr (const jerry_value_t obj_val,
                                const jerry_object_native_info_t *info_p)
  • obj_val - object to delete native pointer from.
  • info_p - native pointer’s type information.

New in version 2.0.

Example

See jerry_object_get_native_ptr for a best-practice example.

See also

jerry_native_ptr_init

Summary

Initialize the references stored in a buffer pointed by a native pointer. The references are initialized to undefined. This function must be called before the buffer is attached to an object by jerry_object_set_native_ptr.

Note:

Prototype

void
jerry_native_ptr_init (void *native_pointer_p,
                       const jerry_object_native_info_t *native_info_p);
  • native_pointer_p - a valid non-NULL pointer to a native buffer.
  • native_info_p - native pointer’s type information.

New in version [[NEXT_RELEASE]].

Example

#include <stdlib.h>
#include "jerryscript.h"

typedef struct
{
  uint32_t user_data;
  jerry_value_t a;
  jerry_value_t b;
  uint32_t user_other_data;
} user_buffer_t;

static void
native_references_free_callback (void *native_p, /**< native pointer */
                                 jerry_object_native_info_t *info_p) /**< native info */
{
  /* References must be finalized when a buffer is no longer attached. */
  jerry_native_ptr_free (native_p, info_p);
  free (native_p);
} /* native_references_free_callback */

static const jerry_object_native_info_t native_info =
{
  .free_cb = native_references_free_callback,
  .number_of_references = 2,
  .offset_of_references = offsetof(user_buffer_t, a),
};

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t object_value = jerry_object ();

  user_buffer_t *buffer_p = (user_buffer_t *) malloc (sizeof (user_buffer_t));

  /* References must be initialized before a buffer is attached. */
  jerry_native_ptr_init ((void *) buffer_p, &native_info);

  jerry_object_set_native_ptr (object_value, &native_info, (void *) buffer_p);

  /* References can be modified after the buffer is attached.
   * This example sets a self reference. */
  jerry_native_ptr_set (&buffer_p->a, object_value);

  jerry_value_free (object_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_native_ptr_free

Summary

Release the value references stored in a buffer pointed by a native pointer. This function must be called after a buffer is no longer attached to any object, even if the buffer is attached to another object again. This function also initializes the values to undefined, so calling jerry_native_ptr_init is optional before the buffer is attached again.

Note:

Prototype

void
jerry_native_ptr_free (void *native_pointer_p,
                       const jerry_object_native_info_t *native_info_p);
  • native_pointer_p - a valid non-NULL pointer to a native buffer.
  • native_info_p - native pointer’s type information.

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_native_ptr_init.

See also

jerry_native_ptr_set

Summary

Updates a value reference inside the area specified by the number_of_references and offset_of_references fields in its corresponding jerry_object_native_info_t data. The area must be part of a buffer which is currently assigned to an object.

Note:

Prototype

void
jerry_native_ptr_set (jerry_value_t *reference_p,
                      jerry_value_t value)
  • reference_p - a valid non-NULL pointer to a reference in a native buffer.
  • value - new value of the reference.

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_native_ptr_init.

See also

jerry_object_property_names

Summary

Gets the property keys for the given object using the selected filters.

Prototype

jerry_value_t
jerry_object_property_names (jerry_value_t obj_val,
                             jerry_property_filter_t filter);
  • obj_val - object value
  • filter - any combination of jerry_property_filter_t options
  • return value
    • array containing the filtered property keys in successful operation
    • exception, otherwise

New in version 2.4.

Example

{
  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t keys = jerry_object_property_names (object, JERRY_PROPERTY_FILTER_ALL);

  ... // usage of keys

  jerry_value_free (keys);
  jerry_value_free (global_object);
}

See also

jerry_object_foreach

Summary

Applies the given function to every enumerable(!) property in the given object.

The “iterator” foreach_p method should return true value to continue the iteration. If the method returns false the iteration will end.

Prototype

bool
jerry_object_foreach (jerry_value_t obj_val,
                      jerry_object_property_foreach_cb_t foreach_p,
                      void *user_data_p);
  • obj_val - object value
  • foreach_p - foreach function, that will be applied for each property
  • user_data_p - user data for foreach function
  • return value
    • true, if object fields traversal was performed successfully, i.e.:
      • no unhandled exceptions were thrown in object fields traversal
      • object fields traversal was stopped on callback that returned false
    • false, otherwise

Example

#include <stdio.h>
#include "jerryscript.h"

/* Example structure used as user data for the property iteration. */
struct iteration_data {
  int string_property_count;
};

/*
 * Example foreach function to print out property names.
 */
static bool
foreach_function (const jerry_value_t prop_name,
                  const jerry_value_t prop_value,
                  void *user_data_p)
{
  if (jerry_value_is_string (prop_name)) {
    jerry_char_t string_buffer[128];
    jerry_size_t copied_bytes = jerry_string_to_buffer (prop_name,
                                                        JERRY_ENCODING_UTF8,
                                                        string_buffer,
                                                        sizeof (string_buffer) - 1);
    string_buffer[copied_bytes] = '\0';

    printf ("Property: %s\n", string_buffer);

    struct iteration_data *data = (struct iteration_data *) user_data_p;
    data->string_property_count++;
  }

  /* return true to continue iteration */
  return true;
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  /* Construct an example object with a single property. */
  jerry_value_t object = jerry_object ();
  {
    jerry_value_t test_property = jerry_string_sz ("DemoProp");
    jerry_value_t test_value = jerry_number (3);
    /* By default all properties added to an object are enumerable. */
    jerry_value_t set_result = jerry_object_set (object, test_property, test_value);
    /* The `set_result` should be checked if it is an exception or not. */
    jerry_value_free (set_result);
    jerry_value_free (test_value);
    jerry_value_free (test_property);
  }

  /* Iterate on the object's properties with the given user data. */
  struct iteration_data user_data = { 0 };

  bool iteration_result = jerry_object_foreach (object, foreach_function, &user_data);
  /* Check and process the `iteration_result` if required. */

  jerry_value_free (object);

  jerry_cleanup ();

  return user_data.string_property_count == 0;
}

See also

jerry_foreach_live_object

Summary

Iterate over all objects available in the engine.

The “iterator” foreach_p method should return true value to continue the search. If the method returns false the search for the object is finished.

Note: Values obtained in foreach_p must be retained using jerry_value_copy.

Prototype

bool
jerry_foreach_live_object (jerry_foreach_live_object_cb_t foreach_p,
                           void *user_data_p);
  • foreach_p - function that will be invoked for each object.
  • user_data_p - User data to pass to the function.
  • return value
    • true, if the search function terminated the traversal by returning false
    • false, if the end of the list of objects was reached

New in version 2.0.

Example

#include <stdio.h>
#include "jerryscript.h"

/* Create a custom structure to guide the search and store the result. */
typedef struct
{
  jerry_value_t property_name;
  jerry_value_t result;
} find_my_object_info_t;

/*
 * Find the first object with the given property.
 */
static bool
find_my_object (const jerry_value_t candidate,
                void *user_data_p)
{
  find_my_object_info_t *info_p = (find_my_object_info_t *) user_data_p;

  /* Check if the given object has the required property. */
  jerry_value_t has_property = jerry_object_has (candidate, info_p->property_name);
  bool object_found = jerry_value_is_true (has_property);

  if (object_found)
  {
    /* We found it, so we copy the value and record it. */
    info_p->result = jerry_value_copy (candidate);
  }

  jerry_value_free (has_property);

  /* If the object was not found continue the search. */
  return !object_found;
} /* find_my_object */

int
main (void)
{
  int return_value = 0;

  /* Initialize JerryScript engine. */
  jerry_init (JERRY_INIT_EMPTY);

  /* Create the test object. */
  {
    jerry_value_t test_object = jerry_object ();

    {
      jerry_value_t test_property = jerry_string_sz ("DemoProp");
      jerry_value_t test_value = jerry_number (3);
      jerry_value_t set_result = jerry_object_set (test_object, test_property, test_value);
      /* The `set_result` should be checked if it is an exception or not. */
      jerry_value_free (set_result);
      jerry_value_free (test_value);
      jerry_value_free (test_property);
    }

    {
      /* Register the test object into the global object. */
      jerry_value_t global_object = jerry_current_realm ();
      jerry_value_t demo_property = jerry_string_sz ("DemoObject");
      jerry_value_t set_result = jerry_object_set (global_object, demo_property, test_object);
      /* The `set_result` should be checked if it is an exception or not. */
      jerry_value_free (set_result);
      jerry_value_free (demo_property);
      jerry_value_free (global_object);
    }

    jerry_value_free (test_object);
  }

  /* Look up the test object base on a property name. */
  find_my_object_info_t search_info =
  {
    .property_name = jerry_string_sz ("DemoProp")
  };

  if (jerry_foreach_live_object (find_my_object, &search_info))
  {
    /* The search was successful. Do something useful with search_info.result. */
    // ...
    printf ("Object found\n");

    /* Release the found object after we're done using it. */
    jerry_value_free (search_info.result);
  }
  else
  {
    /* The search has failed. */
    printf ("Object not found\n");

    return_value = 1;
  }

  jerry_value_free (search_info.property_name);

  /* Engine cleanup */
  jerry_cleanup ();
  return return_value;
}

See also

jerry_foreach_live_object_with_info

Summary

Iterate over all objects in the engine matching a certain native data type.

The “iterator” foreach_p method should return true value to continue the search. If the method returns false the search for the object is finished.

Note: Values obtained in foreach_p must be retained using jerry_value_copy.

Prototype

bool
jerry_foreach_live_object_with_info (const jerry_object_native_info_t *native_info_p,
                                     jerry_foreach_live_object_with_info_cb_t foreach_p,
                                     void *user_data_p);
  • native_info_p - native pointer’s type information.
  • foreach_p - function that will be invoked for each object.
  • return value
    • true, if the search function terminated the traversal by returning false
    • false, if the end of the list of objects was reached

New in version 2.0.

Example

#include <stdio.h>
#include <stdlib.h>
#include "jerryscript.h"

typedef struct
{
  int foo;
  bool bar;
} native_obj_t;

typedef struct
{
  jerry_value_t found_object;
  native_obj_t *found_native_data_p;

  int match_foo_value;
} find_object_data_t;

static void native_freecb (void *native_p,
                           jerry_object_native_info_t *info_p)
{
  (void) info_p;

  /* `native_p` was allocated via malloc. */
  free (native_p);
} /* native_freecb */

/*
 * NOTE: The address (!) of type_info acts as a way to uniquely "identify" the
 * C type `native_obj_t *`.
 */
static const jerry_object_native_info_t native_obj_type_info =
{
  .free_cb = native_freecb
};

/*
 * Function creating JS object that is "backed" by a `native_obj_t`.
 */
static void
add_object_with_nativeptr (int foo_value)
{
  // construct object and native_set value:
  jerry_value_t test_object = jerry_object ();
  native_obj_t *native_obj_p = malloc (sizeof (*native_obj_p));
  native_obj_p->foo = foo_value;
  native_obj_p->bar = true;

  jerry_object_set_native_ptr (test_object, &native_obj_type_info, native_obj_p);

  /* Register the test object into the global object. */
  jerry_value_t global_object = jerry_current_realm ();
  jerry_value_t demo_property = jerry_string_sz ("DemoObject");
  jerry_value_t set_result = jerry_object_set (global_object, demo_property, test_object);
  /* The `set_result` should be checked if it is an exception or not. */
  jerry_value_free (set_result);
  jerry_value_free (demo_property);
  jerry_value_free (global_object);

  jerry_value_free (test_object);
} /* create_object_with_nativeptr */

/*
 * Example native method that searches for a JavaScript object
 * with a `native_obj_type_info` has the correct value.
 */
static bool
find_object (const jerry_value_t candidate, void *data_p, void *user_data_p)
{
  find_object_data_t *find_data_p = (find_object_data_t *) user_data_p;
  native_obj_t *native_obj_p = (native_obj_t *) data_p;

  if (find_data_p->match_foo_value == native_obj_p->foo)
  {
    /* If the object was found, copy it and store it in the user data. */
    find_data_p->found_object = jerry_value_copy (candidate);
    find_data_p->found_native_data_p = native_obj_p;

    /* Stop traversing over the objects. */
    return false;
  }

  /* Indicate that the object was not found, so traversal must continue. */
  return true;
} /* find_object */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  add_object_with_nativeptr (4);
  add_object_with_nativeptr (3);
  add_object_with_nativeptr (2);

  find_object_data_t find_data =
  {
    .match_foo_value = 3,
  };

  if (jerry_foreach_live_object_with_info (&native_obj_type_info, find_object, &find_data))
  {
    /* The object was found and is now stored in `find_data.found_object`. After using it, it must be released. */
    printf ("Object found, native foo value: %d\n", find_data.found_native_data_p->foo);

    jerry_value_free (find_data.found_object);
  }
  else
  {
    printf ("Object not found\n");
  }

  jerry_cleanup ();

  return 0;
}

See also

Input validator functions

jerry_validate_string

Summary

Check if a given character buffer is a valid in the specified encoding string.

Notes: Calling this method is safe in any time. It can be called even before engine initialization.

Prototype

bool
jerry_validate_string (const jerry_char_t *buffer_p, /**< string data */
                       jerry_size_t buf_size, /**< string size */
                       jerry_encoding_t encoding); /**< encoding */
  • buffer_p - input string buffer.
  • buf_size - input string buffer size in bytes.
  • encoding - string encoding
  • return value
    • true, if the provided string was a valid UTF-8 string.
    • false, if the string is not valid as an UTF-8 string.

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  const jerry_char_t script[] = "print ('Hello, World!');";
  const jerry_size_t script_size = sizeof (script) - 1;

  if (!jerry_validate_string (script, script_size, JERRY_ENCODING_CESU8))
  {
    return 1;
  }

  return 0;
}

See also

Dynamic memory management functions

jerry_heap_alloc

Summary

Allocate memory on the engine’s heap.

Note: This function may take away memory from the executed JavaScript code. If any other dynamic memory allocation API is available (e.g., libc malloc), it should be used instead.

Prototype

void *jerry_heap_alloc (size_t size);
  • size: size of the memory block.
  • return value: non-NULL pointer, if the memory is successfully allocated, NULL otherwise.

New in version 2.0.

See also

jerry_heap_free

Summary

Free memory allocated on the engine’s heap.

Prototype

void jerry_heap_free (void *mem_p, size_t size);
  • mem_p: value returned by jerry_heap_alloc.
  • size: same size as passed to jerry_heap_alloc.

New in version 2.0.

See also

Snapshot functions

jerry_generate_snapshot

Summary

Generate snapshot from the specified source code.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_SNAPSHOT_SAVE) and can be checked in runtime with the JERRY_FEATURE_SNAPSHOT_SAVE feature enum value, see jerry_feature_enabled. If the feature is not enabled the function will return an exception.

Prototype

jerry_value_t
jerry_generate_snapshot (jerry_value_t compiled_code,
                         uint32_t generate_snapshot_opts,
                         uint32_t *buffer_p,
                         size_t buffer_size);
  • compiled_code - compiled script or function (see: jerry_parse).
  • generate_snapshot_opts - any combination of jerry_generate_snapshot_opts_t flags.
  • buffer_p - output buffer (aligned to 4 bytes) to save snapshot to.
  • buffer_size - the output buffer’s size in bytes.
  • return value
    • the size of the generated snapshot in bytes as number value, if it was generated successfully (i.e. there are no syntax errors in source code, buffer size is sufficient, and snapshot support is enabled in current configuration through JERRY_SNAPSHOT_SAVE)
    • thrown exception, otherwise.

New in version 2.0.

Changed in version [[NEXT_RELEASE]]: The source_p, source_size, source_name_p, and source_name_length arguments are replaced by compiled_code which should contain a compiled ECMAScript script / function. The jerry_generate_function_snapshot is now removed and can be reproduced by calling jerry_parse with function arguments and using this method (see jerry_exec_snapshot). Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  static uint32_t global_mode_snapshot_buffer[256];
  const jerry_char_t script_to_snapshot[] = "(function () { return 'string from snapshot'; }) ();";

  jerry_value_t parse_result = jerry_parse (script_to_snapshot,
                                            sizeof (script_to_snapshot) - 1,
                                            NULL);

  size_t buffer_size = sizeof (global_mode_snapshot_buffer) / sizeof (uint32_t);
  jerry_value_t generate_result = jerry_generate_snapshot (parse_result,
                                                           0,
                                                           global_mode_snapshot_buffer,
                                                           buffer_size);
  jerry_value_free (parse_result);

  if (!jerry_value_is_exception (generate_result))
  {
    size_t snapshot_size = (size_t) jerry_value_as_number (generate_result);
  }

  jerry_value_free (generate_result);

  jerry_cleanup ();
  return 0;
}

See also

jerry_exec_snapshot

Summary

Execute/load snapshot from the specified buffer.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API depends on a build option (JERRY_SNAPSHOT_EXEC) and can be checked in runtime with the JERRY_FEATURE_SNAPSHOT_EXEC feature enum value, see jerry_feature_enabled. If the feature is not enabled the function will return an exception.

Prototype

jerry_value_t
jerry_exec_snapshot (const uint32_t *snapshot_p,
                     size_t snapshot_size,
                     size_t func_index,
                     uint32_t exec_snapshot_opts,
                     const jerry_exec_snapshot_option_values_t *options_values_p);
  • snapshot_p - pointer to snapshot.
  • snapshot_size - size of snapshot in bytes.
  • func_index - index of executed function.
  • exec_snapshot_opts - any combination of jerry_exec_snapshot_opts_t flags.
  • options_values_p - additional loading options, can be NULL if not used. The fields are described in jerry_exec_snapshot_option_values_t.
  • return value
    • result of bytecode, if run was successful.
    • thrown exception, otherwise (an exception is reported if the snapshot execution feature is not enabled).

Changed in version 2.0: Added func_index and exec_snapshot_opts arguments. Removed the copy_bytecode last argument.

Changed in version [[NEXT_RELEASE]]: Added options_p argument.

Example 1

#include "jerryscript.h"

int
main (void)
{
  static uint32_t snapshot_buffer[256];

  /* 1st example: global mode snapshot. */
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script_to_snapshot[] = "(function () { return 'string from snapshot'; }) ();";

  jerry_value_t parse_result = jerry_parse (script_to_snapshot,
                                            sizeof (script_to_snapshot) - 1,
                                            NULL);

  size_t buffer_size = sizeof (snapshot_buffer) / sizeof (uint32_t);
  jerry_value_t generate_result = jerry_generate_snapshot (parse_result,
                                                           0,
                                                           snapshot_buffer,
                                                           buffer_size);
  jerry_value_free (parse_result);

  /* 'generate_result' variable should be checked whether it contains an exception. */

  size_t snapshot_size = (size_t) jerry_value_as_number (generate_result);
  jerry_value_free (generate_result);

  jerry_cleanup ();
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t res = jerry_exec_snapshot (snapshot_buffer,
                                           snapshot_size,
                                           0,
                                           0,
                                           NULL);

  /* 'res' now contains 'string from snapshot' */
  jerry_value_free (res);

  jerry_cleanup ();
  return 0;
}

Example 2

#include "jerryscript.h"

int
main (void)
{
  static uint32_t snapshot_buffer[256];

  /* 2nd example: function snapshot. */
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t function_to_snapshot[] = "return a + b;";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_ARGUMENT_LIST;
  parse_options.argument_list = jerry_string_sz ("a, b");

  jerry_value_t parse_result = jerry_parse (function_to_snapshot,
                                            sizeof (function_to_snapshot) - 1,
                                            &parse_options);

  size_t buffer_size = sizeof (snapshot_buffer) / sizeof (uint32_t);
  jerry_value_t generate_result = jerry_generate_snapshot (parse_result,
                                                           0,
                                                           snapshot_buffer,
                                                           buffer_size);
  jerry_value_free (parse_result);
  jerry_value_free (parse_options.argument_list);

  /* 'generate_result' variable should be checked whether it contains an exception. */

  size_t snapshot_size = (size_t) jerry_value_as_number (generate_result);
  jerry_value_free (generate_result);

  jerry_cleanup ();
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t func = jerry_exec_snapshot (snapshot_buffer,
                                            snapshot_size,
                                            0,
                                            JERRY_SNAPSHOT_EXEC_LOAD_AS_FUNCTION,
                                            NULL);
  /* 'func' can be used now as a function object. */

  jerry_value_t this_value = jerry_undefined ();
  jerry_value_t args[2];
  args[0] = jerry_number (1.0);
  args[1] = jerry_number (2.0);

  jerry_value_t res = jerry_call (func, this_value, args, 2);

  /* 'res' now contains the value 3 as a jerry_value_t. */
  jerry_value_free (res);
  jerry_value_free (args[0]);
  jerry_value_free (args[1]);
  jerry_value_free (this_value);
  jerry_value_free (func);

  jerry_cleanup ();
  return 0;
}

See also

jerry_get_literals_from_snapshot

Summary

Collect the used literals from the given snapshot and save them into a buffer in list or C format. None of these literals are magic strings. In C format only valid identifiers are collected.

Note:

  • This API depends on a build option (JERRY_SNAPSHOT_SAVE) and can be checked in runtime with the JERRY_FEATURE_SNAPSHOT_SAVE feature enum value, see jerry_feature_enabled. If the feature is not enabled the function will return zero.

Prototype

size_t
jerry_get_literals_from_snapshot (const uint32_t *snapshot_p,
                                  size_t snapshot_size,
                                  jerry_char_t *lit_buf_p,
                                  size_t lit_buf_size,
                                  bool is_c_format);
  • snapshot_p - input snapshot buffer.
  • snapshot_size - size of snapshot in bytes.
  • lit_buf_p - buffer to save literals to.
  • lit_buf_size - the buffer’s size.
  • is_c_format - the output format would be C-style (true) or a simple list (false).
  • return value
    • the size of the literal-list, if it was generated successfully (i.e. the list of literals isn’t empty, and literal-save support is enabled in current configuration through JERRY_SNAPSHOT_SAVE)
    • 0 otherwise.

New in version 2.0.

Example

#include <stdio.h>
#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  static jerry_char_t literal_buffer[256];
  static uint32_t snapshot_buffer[256];
  const jerry_char_t script_for_literal_save[] = "var obj = { a:'aa', bb:'Bb' }";

  jerry_value_t parse_result = jerry_parse (script_for_literal_save,
                                            sizeof (script_for_literal_save) - 1,
                                            NULL);

  size_t buffer_size = sizeof (snapshot_buffer) / sizeof (uint32_t);
  jerry_value_t generate_result = jerry_generate_snapshot (parse_result,
                                                           0,
                                                           snapshot_buffer,
                                                           buffer_size);
  jerry_value_free (parse_result);

  size_t snapshot_size = (size_t) jerry_value_as_number (generate_result);
  jerry_value_free (generate_result);

  const size_t literal_size = jerry_get_literals_from_snapshot (snapshot_buffer,
                                                                snapshot_size,
                                                                literal_buffer,
                                                                256,
                                                                true);

  if (literal_size != 0)
  {
    FILE *literal_file_p = fopen ("literals.h", "wb");
    fwrite (literal_buffer, sizeof (uint8_t), literal_size, literal_file_p);
    fclose (literal_file_p);
  }

  jerry_cleanup ();
  return 0;
}

See also

Backtrace functions

jerry_backtrace

Summary

Get backtrace. The backtrace is an array of strings where each string contains the position of the corresponding frame. The array length is zero if the backtrace is not available.

This function is typically called from native callbacks.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This feature depends on build option (JERRY_LINE_INFO) and can be checked in runtime with the JERRY_FEATURE_LINE_INFO feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t
jerry_backtrace (uint32_t max_depth);
  • max_depth - backtrace collection stops after reaching this value, 0 = unlimited
  • return value
    • a newly constructed JS array

New in version 2.0.

Example

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static jerry_value_t
backtrace_handler (const jerry_call_info_t *call_info_p,
                   const jerry_value_t args_p[],
                   const jerry_length_t args_count)
{
  if (!jerry_feature_enabled (JERRY_FEATURE_LINE_INFO))
  {
    printf ("Line info disabled, no backtrace will be printed\n");
    return jerry_undefined ();
  }

  /* If the line info feature is disabled an empty array will be returned. */
  jerry_value_t backtrace_array = jerry_backtrace (5);
  uint32_t array_length = jerry_array_length (backtrace_array);

  for (uint32_t idx = 0; idx < array_length; idx++)
  {
    jerry_value_t property = jerry_object_get_index (backtrace_array, idx);

    jerry_char_t string_buffer[64];
    jerry_size_t copied_bytes = jerry_string_to_buffer (property,
                                                        JERRY_ENCODING_UTF8,
                                                        string_buffer,
                                                        sizeof (string_buffer) - 1);
    string_buffer[copied_bytes] = '\0';
    printf(" %d: %s\n", idx, string_buffer);

    jerry_value_free (property);
  }

  jerry_value_free (backtrace_array);

  return jerry_undefined ();
} /* backtrace_handler */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global = jerry_current_realm ();

  /* Register the "capture_backtrace" method. */
  {
    jerry_value_t func = jerry_function_external (backtrace_handler);
    jerry_value_t name = jerry_string_sz ("backtrace");
    jerry_value_t result = jerry_object_set (global, name, func);
    jerry_value_free (result);
    jerry_value_free (name);
    jerry_value_free (func);
  }

  jerry_value_free (global);

  const char *source = ("function f() { g (); }\n"
                        "function g() { h (); }\n"
                        "function h() { backtrace (); }\n"
                        "f ();\n");

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("demo_memory.js");

  jerry_value_t program = jerry_parse ((const jerry_char_t *) source,
                                       strlen (source),
                                       &parse_options);
  jerry_value_free (parse_options.source_name);

  if (!jerry_value_is_exception (program))
  {
    jerry_value_t run_result = jerry_run (program);
    jerry_value_free (run_result);
  }

  jerry_value_free (program);
  jerry_cleanup ();

  return 0;
}

See also

jerry_backtrace_capture

Summary

Low-level function to capture each backtrace frame. The captured frame data is passed to a callback function. To improve performance, the majority of the frame data is not initialized when the callback function is called. The initialization of these fields can be done later by helper functions such as jerry_frame_location.

Prototype

void
jerry_backtrace_capture (jerry_backtrace_cb_t callback, void *user_p);
  • callback - a jerry_backtrace_cb_t callback which is called for each captured frame
  • user_p - pointer passed to the callback function, can be NULL

New in version [[NEXT_RELEASE]].

Example

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  printf (" A stack frame is captured\n");
  return true;
}

static jerry_value_t
backtrace_handler (const jerry_call_info_t *call_info_p,
                   const jerry_value_t args_p[],
                   const jerry_length_t args_count)
{
  (void) call_info_p;
  (void) args_p;
  (void) args_count;

  jerry_backtrace_capture (&backtrace_callback, NULL);

  return jerry_undefined ();
} /* backtrace_handler */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global = jerry_current_realm ();

  /* Register the "dump_backtrace" method. */
  {
    jerry_value_t func = jerry_function_external (backtrace_handler);
    jerry_value_t name = jerry_string_sz ("backtrace");
    jerry_value_t result = jerry_object_set (global, name, func);
    jerry_value_free (result);
    jerry_value_free (name);
    jerry_value_free (func);
  }

  jerry_value_free (global);

  const char *source = ("function f() { g (); }\n"
                        "function g() { h (); }\n"
                        "function h() { backtrace (g); }\n"
                        "f ();\n");

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("demo_backtrace.js");

  jerry_value_t program = jerry_parse ((const jerry_char_t *) source,
                                       strlen (source),
                                       &parse_options);
  jerry_value_free (parse_options.source_name);

  if (!jerry_value_is_exception (program))
  {
    jerry_value_t run_result = jerry_run (program);
    jerry_value_free (run_result);
  }

  jerry_value_free (program);
  jerry_cleanup ();

  return 0;
}

See also

jerry_frame_type

Summary

Returns with the type of the backtrace frame. This function can only be called from the callback function of jerry_backtrace_capture, and the value becomes invalid after the callback returns.

Prototype

jerry_frame_type_t
jerry_frame_type (jerry_frame_t *frame_p);

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_backtrace_capture with the following callback function:

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  switch (jerry_frame_type (frame_p))
  {
    case JERRY_BACKTRACE_FRAME_JS:
    {
      printf (" ECMAScript frame\n");
      break;
    }
    default:
    {
      printf (" Other frame\n");
      break;
    }
  }

  return true;
}

See also

jerry_frame_location

Summary

Initialize and return with the location private field of a backtrace frame. If the location is not available, the returned value is NULL. This function can only be called from the callback function of jerry_backtrace_capture, and the value becomes invalid after the callback returns.

Notes:

  • Location information can only be retrieved if JERRY_FEATURE_LINE_INFO feature is enabled. Otherwise the function always returns with NULL.
  • The returned data must not be modified, and does not need to be freed. Any cleanup is done automatically after the callback is returned.

Prototype

const jerry_frame_location_t *
jerry_frame_location (jerry_frame_t *frame_p);
  • frame_p - a frame passed to the jerry_backtrace_cb_t callback
  • return value
    • pointer to the location private field if the location is available,
    • NULL otherwise

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_backtrace_capture with the following callback function:

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  const jerry_frame_location_t *location_p;
  location_p = jerry_frame_location (frame_p);

  if (location_p == NULL)
  {
    printf ("No location info is available\n");
    return true;
  }

  jerry_char_t string_buffer[64];
  jerry_size_t copied_bytes = jerry_string_to_buffer (location_p->source_name,
                                                      JERRY_ENCODING_UTF8
                                                      string_buffer,
                                                      sizeof (string_buffer) - 1);
  string_buffer[copied_bytes] = '\0';
  printf(" %s:%d:%d\n", string_buffer, (int) location_p->line, (int) location_p->column);
  return true;
}

See also

jerry_frame_callee

Summary

Initialize and return with the called function private field of a backtrace frame. The backtrace frame is created for running the code bound to this function. This function can only be called from the callback function of jerry_backtrace_capture, and the value becomes invalid after the callback returns.

Notes:

  • The returned data must not be modified, and does not need to be freed. Any cleanup is done automatically after the callback is returned.

Prototype

const jerry_value_t *
jerry_frame_callee (jerry_frame_t *frame_p);
  • frame_p - a frame passed to the jerry_backtrace_cb_t callback
  • return value
    • pointer to the called function if the function is available,
    • NULL otherwise

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_backtrace_capture with the following callback function:

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  jerry_value_t *function_p = jerry_frame_callee (frame_p);

  if (function_p != NULL)
  {
    printf ("Called function is available");
    return true;
  }

  printf ("Called function is NOT available");
  return true;
}

See also

jerry_frame_this

Summary

Initialize and return with the ‘this’ binding private field of a backtrace frame. The ‘this’ binding is a hidden value passed to the called function. As for arrow functions, the ‘this’ binding is assigned at function creation. This getter function can only be called from the callback function of jerry_backtrace_capture, and the value becomes invalid after the callback returns.

Notes:

  • The returned data must not be modified, and does not need to be freed. Any cleanup is done automatically after the callback is returned.

Prototype

const jerry_value_t *
jerry_frame_this (jerry_frame_t *frame_p);
  • frame_p - a frame passed to the jerry_backtrace_cb_t callback
  • return value
    • pointer to the ‘this’ binding if the binding is available,
    • NULL otherwise

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_backtrace_capture with the following callback function:

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  jerry_value_t *this_p = jerry_frame_this (frame_p);

  if (this_p != NULL)
  {
    printf ("The 'this' binding is available");
    return true;
  }

  printf ("The 'this' binding is NOT available");
  return true;
}

See also

jerry_frame_is_strict

Summary

Returns true, if the code bound to the backtrace frame is strict mode code. This function can only be called from the callback function of jerry_backtrace_capture, and the value becomes invalid after the callback returns.

Prototype

bool
jerry_frame_is_strict (jerry_frame_t *frame_p);
  • frame_p - a frame passed to the jerry_backtrace_cb_t callback
  • return value
    • true, if strict mode code is bound to the frame
    • false, otherwise

New in version [[NEXT_RELEASE]].

Example

See the example of jerry_backtrace_capture with the following callback function:

static bool
backtrace_callback (jerry_frame_t *frame_p,
                    void *user_p)
{
  if (jerry_frame_is_strict (frame_p))
  {
    printf ("Strict mode code is running");
    return true;
  }

  printf ("Non-strict mode code is running");
  return true;
}

See also

Miscellaneous functions

jerry_halt_handler

Summary

The callback passed to this function is periodically called when JerryScript executes an ECMAScript program.

If the callback returns with undefined value the ECMAScript execution continues. Otherwise the result is thrown by the engine. The callback function might be called again even if it threw an exception. In this case the function must throw the same exception again.

To reduce the CPU overhead of constantly checking the termination condition the callback is called when a backward jump is executed or an exception is caught. Setting the interval to a greater than 1 value reduces this overhead further. If its value is N only every Nth event (backward jump, etc.) trigger the next check.

Notes:

  • This API depends on a build option (JERRY_VM_HALT) and can be checked in runtime with the JERRY_FEATURE_VM_EXEC_STOP feature enum value, see: jerry_feature_enabled.

Prototype

void
jerry_halt_handler (uint32_t interval,
                    jerry_halt_cb_t callback
                    void *user_p);
  • interval - interval of calling the callback function
  • callback - periodically called callback (passing NULL disables this feature)
  • user_p - user pointer passed to the callback function

New in version 2.0.

Example

#include "jerryscript.h"

static jerry_value_t
vm_exec_stop_callback (void *user_p)
{
  int *countdown_p = (int *) user_p;

  while (*countdown_p > 0)
  {
    (*countdown_p)--;
    return jerry_undefined ();
  }

  // The value will be automatically wrapped into an exception.
  return jerry_string_sz ("Abort script");
}

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  int countdown = 10;
  jerry_halt_handler (16, vm_exec_stop_callback, &countdown);

  // Infinite loop.
  const jerry_char_t script[] = "while(true) {}";

  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, NULL);
  jerry_value_free (jerry_run (parsed_code));
  jerry_value_free (parsed_code);
  jerry_cleanup ();
}

See also

jerry_source_name

Summary

Get the source name (usually a file name) of the currently executed script or the given function object.

This function is typically called from native callbacks.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This feature depends on build option (JERRY_LINE_INFO) and can be checked in runtime with the JERRY_FEATURE_LINE_INFO feature enum value, see: jerry_feature_enabled.

Prototype

jerry_value_t
jerry_source_name (jerry_value_t value);
  • value - api value to obtain the source name from
  • return string value constructed from
    • the currently executed function object’s source name, if the given value is undefined
    • source name of the function object, if the given value is a function object
    • “", otherwise

New in version 2.2.

Example

#include <stdio.h>
#include <string.h>
#include "jerryscript.h"

static jerry_value_t
source_name_handler (const jerry_call_info_t *call_info_p,
                     const jerry_value_t args_p[],
                     const jerry_length_t args_count)
{
  jerry_value_t undefined_value = jerry_undefined ();
  jerry_value_t source_name = jerry_source_name (args_count > 0 ? args_p[0] : undefined_value);
  jerry_value_free (undefined_value);

  return source_name;
} /* source_name_handler */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t global = jerry_current_realm ();

  /* Register the sourceName" method. */
  {
    jerry_value_t func = jerry_function_external (source_name_handler);
    jerry_value_t name = jerry_string_sz ("sourceName");
    jerry_value_t result = jerry_object_set (global, name, func);
    jerry_value_free (result);
    jerry_value_free (name);
    jerry_value_free (func);
  }

  jerry_value_free (global);

  const jerry_char_t source[] = "function myFunction() { return sourceName() }; myFunction()";

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_SOURCE_NAME;
  parse_options.source_name = jerry_string_sz ("demo.js");

  jerry_value_t program = jerry_parse (source,
                                       sizeof (source) - 1,
                                       &parse_options);
  jerry_value_free (parse_options.source_name);

  if (!jerry_value_is_exception (program))
  {
    /* `run_result` contains "demo.js" */
    jerry_value_t run_result = jerry_run (program);

    /* usage of `run_result` */

    jerry_value_free (run_result);
  }

  jerry_value_free (program);
  jerry_cleanup ();

  return 0;
}

See also

jerry_source_user_value

Summary

Returns the user value assigned to a script / module / function. This value is set by the parser when the JERRY_PARSE_HAS_USER_VALUE flag is set in the options member of the jerry_parse_options_t structure.

Notes:

  • Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_source_user_value (const jerry_value_t value);
  • value - script / module / function value which executes ECMAScript code (native modules / functions do not have user value).
  • return
    • user value - if available,
    • undefined - otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "function abc() {} abc";

  jerry_value_t user_value = jerry_object ();

  jerry_parse_options_t parse_options;
  parse_options.options = JERRY_PARSE_HAS_USER_VALUE;
  parse_options.user_value = user_value;

  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, &parse_options);
  jerry_value_free (user_value);

  /* The jerry_source_user_value returns the object which
   * was created by jerry_object before. */

  user_value = jerry_source_user_value (parsed_code);
  jerry_value_free (parsed_code);

  jerry_value_free (user_value);
  jerry_cleanup ();
  return 0;
}

See also

jerry_function_is_dynamic

Summary

Checks whether an ECMAScript code is compiled by eval like (eval, new Function, jerry_eval, etc.) command.

Prototype

bool jerry_function_is_dynamic (const jerry_value_t value);
  • value - script / module / function value which executes ECMAScript code
  • return
    • true - if code is compiled by eval like command
    • false - otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "eval('(function (a) { return a; })')";

  jerry_value_t script_value = jerry_parse (script, sizeof (script) - 1, NULL);
  jerry_value_t function_value = jerry_run (script_value);
  jerry_value_free (script_value);

  if (jerry_function_is_dynamic (function_value))
  {
    /* Code enters here. */
  }

  jerry_value_free (function_value);
  jerry_cleanup ();
  return 0;
}

See also

jerry_source_info

Summary

Returns a newly created source info structure corresponding to the passed script/module/function. The function is lower level than toString() operation, but provides more contextual information.

Notes:

  • Returned value must be freed with jerry_source_info_free when it is no longer needed.
  • This API depends on a build option (JERRY_FUNCTION_TO_STRING) and can be checked in runtime with the JERRY_FEATURE_FUNCTION_TO_STRING feature enum value, see: jerry_feature_enabled.

Prototype

jerry_source_info_t *jerry_source_info (const jerry_value_t value);
  • value - script / module / function value which executes JavaScript code (native modules / functions do not have source info).
  • return
    • source info - a newly created source info, if at least one field is available,
    • NULL - otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t script[] = "function abc() {} abc";

  jerry_value_t parsed_code = jerry_parse (script, sizeof (script) - 1, NULL);

  jerry_source_info_t *source_info_p = jerry_source_info (parsed_code);
  jerry_value_free (parsed_code);

  if (source_info_p != NULL)
  {
    /* Check the information provided by jerry_source_info. */
  }

  jerry_source_info_free (source_info_p);

  jerry_cleanup ();
  return 0;
}

See also

jerry_source_info_free

Summary

Frees the the source info structure returned by jerry_source_info.

Notes:

  • This API depends on a build option (JERRY_FUNCTION_TO_STRING) and can be checked in runtime with the JERRY_FEATURE_FUNCTION_TO_STRING feature enum value, see: jerry_feature_enabled.

Prototype

void jerry_source_info_free (jerry_source_info_t *source_info_p)

New in version [[NEXT_RELEASE]].

Example

See jerry_source_info

See also

Functions for realm objects

These APIs all depend on build option (JERRY_BUILTIN_REALMS).

jerry_set_realm

Summary

Replaces the currently active realm (including the global object) with another realm. The replacement should be temporary, and the original realm must be restored after the tasks are completed. During the replacement, the realm must be referenced by the application (i.e. the gc must not reclaim it). This is also true to the returned previously active realm, so there is no need to free the value after the restoration. The function can only fail if realms are not supported or the passed argument is not a realm. In this case the returned exception must be freed by jerry_value_free.

This function is useful to parse a script, create a native function, load a snapshot or create an exception in another realm. Each ECMAScript code runs in the realm which was active when the code was parsed or loaded regardless of the current realm.

Notes:

  • This feature depends on build option (JERRY_BUILTIN_REALMS) and can be checked in runtime with the JERRY_FEATURE_REALM feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_set_realm (jerry_value_t realm_value);
  • realm_value - the new realm value
  • return
    • previous realm value - if the passed value is a realm
    • exception - otherwise

New in version 2.4.

Example

{
  jerry_value_t realm_value = jerry_realm ();

  jerry_value_t old_realm = jerry_set_realm (realm_value);

  ... // usage of the realm

  jerry_set_realm (old_realm);
}

See also

jerry_realm_this

Summary

Gets the ‘this’ binding of a realm. The ‘this’ binding is always an object. By default the ‘this’ binding is the same as the realm object and can be changed by jerry_realm_set_this.

Notes:

  • This feature depends on build option (JERRY_BUILTIN_REALMS) and can be checked in runtime with the JERRY_FEATURE_REALM feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_realm_this (jerry_value_t realm_value)
  • realm_value - realm value
  • return
    • type error exception- if realm_value is not a realm
    • ‘this’ binding object - otherwise

New in version 2.4.

Example

{
  jerry_value_t realm_value = jerry_realm ();

  jerry_value_t this_value = jerry_realm_this (realm_value);

  ... // usage of the this_value

  jerry_value_free (this_value);
  jerry_value_free (realm_value);
}

See also

jerry_realm_set_this

Summary

Sets the ‘this’ binding of a realm. This function must be called before executing any script on the realm. Otherwise the operation is undefined.

Notes:

  • This feature depends on build option (JERRY_BUILTIN_REALMS) and can be checked in runtime with the JERRY_FEATURE_REALM feature enum value, see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_realm_set_this (jerry_value_t realm_value, jerry_value_t this_value)
  • realm_value - realm value
  • this_value - new this value
  • return
    • type error exception- if realm_value is not a realm or this_value is not object
    • true - otherwise

New in version 2.4.

Example

{
  jerry_value_t realm_value = jerry_realm ();

  jerry_value_t old_realm = jerry_set_realm (realm_value);
  /* The prototype of the object comes from the new realm. */
  jerry_value_t this_value = jerry_object ();
  jerry_set_realm (old_realm);

  jerry_value_t result = jerry_realm_set_this (realm_value, this_value);

  ... // usage of the realm
}

See also

ArrayBuffer and TypedArray functions

These APIs all depend on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.

jerry_arraybuffer_size

Summary

Get the byte length property of the ArrayBuffer or SharedArrayBuffer. This is the same value which was passed to the ArrayBuffer constructor call.

Prototype

jerry_length_t
jerry_arraybuffer_size (const jerry_value_t value);
  • value - ArrayBuffer object
  • return value
    • size of the ArrayBuffer in bytes
    • 0 if the value parameter is not an ArrayBuffer

New in version 2.0.

Example

{
  jerry_value_t buffer = jerry_arraybuffer (15);
  jerry_length_t length = jerry_arraybuffer_size (buffer);
  // length should be 15

  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_read

Summary

Copy the portion of the ArrayBuffer or SharedArrayBuffer into a user provided buffer. The start offset of the read operation can be specified.

The number bytes to be read can be specified via the buf_size parameter. It is not possible to read more than the length of the ArrayBuffer.

Function returns the number of bytes read from the ArrayBuffer (and written to the buffer parameter). This value is calculated in the following way: min(array buffer length - offset, buf_size).

Prototype

jerry_length_t
jerry_arraybuffer_read (const jerry_value_t value,
                        jerry_length_t offset,
                        uint8_t *buf_p,
                        jerry_length_t buf_size);
  • value - ArrayBuffer to read from
  • offset - start offset of the read operation
  • buf_p - buffer to read the data to
  • buf_size - maximum number of bytes to read into the buffer
  • return value
    • number of bytes written into the buffer (read from the ArrayBuffer)
    • 0 if the value is not an ArrayBuffer object
    • 0 if the buf_size is zero or there is nothing to read

New in version 2.0.

Example

{
  uint8_t data[20];
  jerry_value_t buffer;
  // ... create the ArrayBuffer or copy it from somewhere.

  jerry_value_t bytes_read;

  // read 10 bytes from the start of the ArrayBuffer.
  bytes_read = jerry_arraybuffer_read (buffer, 0, data, 10);
  // read the next 10 bytes
  bytes_read += jerry_arraybuffer_read (buffer, bytes_read, data + bytes_read, 10);

  // process the data variable

  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_write

Summary

Copy the contents of a buffer into the ArrayBuffer or SharedArrayBuffer. The start offset of the write operation can be specified.

The number bytes to be written can be specified via the buf_size parameter. It is not possible to write more than the length of the ArrayBuffer.

Function returns the number of bytes written into the ArrayBuffer (and read from the buffer parameter). This value is calculated in the following way: min(array buffer length - offset, buf_size).

Prototype

jerry_length_t
jerry_arraybuffer_write (const jerry_value_t value,
                         jerry_length_t offset,
                         const uint8_t *buf_p,
                         jerry_length_t buf_size);
  • value - ArrayBuffer to write to
  • offset - start offset of the write operation
  • buf_p - buffer to read the data from
  • buf_size - maximum number of bytes to write into the ArrayBuffer
  • return value
    • number of bytes written into the ArrayBuffer (read from the buffer parameter)
    • 0 if the value is not an ArrayBuffer object
    • 0 if the buf_size is zero or there is nothing to write

New in version 2.0.

Example

{
  uint8_t data[20];

  // fill the data with values
  for (int i = 0; i < 20; i++)
  {
    data[i] = (uint8_t) (i * 2);
  }

  jerry_value_t buffer;
  // ... create the ArrayBuffer or copy it from somewhere.

  jerry_value_t bytes_written;

  // write 10 bytes from to the start of the ArrayBuffer.
  bytes_written = jerry_arraybuffer_write (buffer, 0, data, 10);
  // read the next 10 bytes
  bytes_written += jerry_arraybuffer_write (buffer, bytes_written, data + bytes_written, 10);

  // use the ArrayBuffer

  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_data

Summary

The function allows access to the contents of the Array Buffer directly.

WARNING! This operation is for expert use only! The programmer must ensure that the returned memory area is used correctly. That is there is no out of bounds reads or writes. The lifetime of the underlying data buffer is managed by the ArrayBuffer value. Make sure to copy the value with jerry_value_copy if the data buffer is needed later.

Prototype

uint8_t *
jerry_arraybuffer_data (const jerry_value_t value);
  • value - Array Buffer object.
  • return value
    • pointer to the Array Buffer’s data area.
    • NULL if the value is:
      • not an ArrayBuffer object
      • an external ArrayBuffer has been detached

New in version 2.0.

Example

{
  // create the ArrayBuffer
  jerry_value_t buffer = jerry_arraybuffer (16);

  uint8_t *const data = jerry_arraybuffer_data (buffer);

  for (int i = 0; i < 16; i++)
  {
    data[i] = (uint8_t) (i + 4);
  }

  // use the Array Buffer

  // release buffer as it is not needed after this point
  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_is_detachable

Summary

Get if the ArrayBuffer is detachable.

Prototype

bool
jerry_arraybuffer_is_detachable (const jerry_value_t value);
  • value - ArrayBuffer to be detached
  • return
    • true if the arraybuffer is detachable
    • false otherwise

New in version 2.2.

Example

{
  // create the ArrayBuffer
  jerry_value_t buffer = jerry_arraybuffer (16);

  bool is_detachable = jerry_arraybuffer_is_detachable (buffer);

  // release buffer as it is not needed after this point
  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_detach

Summary

Detach the underlying data block from ArrayBuffer and set its bytelength to 0.

This operation requires the ArrayBuffer to be an external buffer created by jerry_arraybuffer_external.

Prototype

jerry_value_t
jerry_arraybuffer_detach (const jerry_value_t value);

Note: If the ArrayBuffer has been created with jerry_arraybuffer_external the optional free callback is called on a successful detach operation

  • value - ArrayBuffer to be detached
  • return
    • null value if success
    • exception otherwise

New in version 2.2.

Example

{
  uint8_t buf[1];
  jerry_size_t length = 1;
  // create the ArrayBuffer
  jerry_value_t buffer = jerry_arraybuffer (length, buf, NULL);

  jerry_value_t res = jerry_arraybuffer_detach (buffer);

  // release buffer as it is not needed after this point
  jerry_value_free (res);
  jerry_value_free (buffer);
}

See also

jerry_arraybuffer_has_buffer

Summary

Checks whether a buffer is currently allocated for an array buffer or typed array.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.

Prototype

bool
jerry_arraybuffer_has_buffer (const jerry_value_t value);
  • value - array buffer or typed array value.
  • return
    • true, if a buffer is allocated for an array buffer or typed array
    • false, otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t array_buffer_value = jerry_arraybuffer (1024 * 1024);

  /* By default, the backing store of large array buffers
   * is allocated when it is used the first time. */

  if (!jerry_arraybuffer_has_buffer (array_buffer_value))
  {
    /* Code enters here in this case. */
  }

  jerry_value_free (array_buffer_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_arraybuffer_heap_allocation_limit

Summary

Array buffers which size is less or equal than the limit passed to this function are allocated in a single memory block. The allocator callbacks set by jerry_arraybuffer_set_allocation_callbacks are not called for these array buffers.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • The default limit is 256 bytes.
  • When an array buffer is allocated in a single memory block, its backing store is not freed when the array buffer is detached.
  • This limit does not affect shared array buffers, their backing store is always allocated by the allocator callback.

Prototype

void
jerry_arraybuffer_heap_allocation_limit (const jerry_length_t allocation_limit);
  • allocation_limit - maximum size of compact allocation.

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_arraybuffer_heap_allocation_limit (1);

  jerry_value_t array_buffer_value = jerry_arraybuffer (1);

  if (jerry_arraybuffer_has_buffer (array_buffer_value))
  {
    /* Code enters here because the backing store
     * is allocated during buffer creation. */
  }

  jerry_value_free (array_buffer_value);

  array_buffer_value = jerry_arraybuffer (2);

  if (jerry_arraybuffer_has_buffer (array_buffer_value))
  {
    /* Code does not enter here because the backing store
     * is allocated when it is used the first time. */
  }

  jerry_value_free (array_buffer_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_arraybuffer_allocator

Summary

Set callbacks for allocating and freeing backing stores for array buffer objects.

Notes:

  • This API depends on a build option (JERRY_BUILTIN_TYPEDARRAY) and can be checked in runtime with the JERRY_FEATURE_TYPEDARRAY feature enum value, see: jerry_feature_enabled.
  • This function is recommended to be called after jerry_init before any array buffer is allocated.
  • The callbacks can be NULL to use the default callbacks. The default allocate_callback allocates memory using jerry_heap_alloc and the default free_callback frees memory using jerry_heap_free.

Prototype

void
jerry_arraybuffer_allocator (jerry_arraybuffer_allocate_cb_t allocate_callback,
                             jerry_arraybuffer_free_cb_t free_callback,
                             void *user_p)
  • allocate_callback - callback for allocating array buffer memory.
  • free_callback - callback for freeing array buffer memory.
  • user_p - user pointer passed to the callbacks.

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

static uint8_t global_buffer[64];

static void
array_buffer_free_cb (jerry_arraybuffer_type_t buffer_type, /**< type of the array buffer object */
                      uint8_t *buffer_p, /**< pointer to the allocated buffer */
                      uint32_t buffer_size, /**< size of the allocated buffer */
                      void *arraybuffer_user_p, /**< user pointer assigned to the array buffer object */
                      void *user_p) /**< user pointer passed to jerry_arraybuffer_set_allocation_callbacks */
{
  (void) buffer_type;
  (void) user_p;

  /* As for this example, only the free callback is redirected. This callback
   * function does not free the memory if the arraybuffer_user_p is non-NULL. */

  if (arraybuffer_user_p == NULL)
  {
    jerry_heap_free (buffer_p, buffer_size);
  }
} /* array_buffer_free_cb */

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_arraybuffer_allocator (NULL, array_buffer_free_cb, NULL);

  /* The buffer of the array buffer object is allocated by the default
   * allocator using jerry_heap_alloc and freed by array_buffer_free_cb. */

  const jerry_char_t script[] = "var result = new uint32Array(1024); result[0] = 1; result";
  jerry_value_t array_buffer_value = jerry_eval (script, sizeof (script) - 1, JERRY_PARSE_NO_OPTS);
  jerry_value_free (array_buffer_value);

  /* The buffer of the array buffer object has a non-NULL
   * arraybuffer_user_p value, so it is not freed by array_buffer_free_cb. */

  array_buffer_value = jerry_arraybuffer_external (global_buffer, sizeof (global_buffer), global_buffer);
  jerry_value_free (array_buffer_value);

  jerry_cleanup ();
  return 0;
}

See also

jerry_dataview_buffer

Summary

Get the ArrayBuffer object used by a DataView object. Additionally returns the byteLength and byteOffset properties of the DataView object.

For the returned ArrayBuffer the jerry_value_free must be called when it is no longer needed.

Prototype

jerry_value_t
jerry_dataview_buffer (const jerry_value_t value,
                       jerry_length_t *byteOffset,
                       jerry_length_t *byteLength);
  • value - DataView to get the ArrayBuffer from
  • byteOffset - (Optional) returns the start offset of the ArrayBuffer for the DataView
  • byteLength - (Optional) returns the number of bytes used from the ArrayBuffer for the DataView
  • return
    • DataView object’s underlying ArrayBuffer object
    • TypeError if the value is not a DataView object

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t arraybuffer = jerry_arraybuffer (16);
  jerry_value_t dataview = jerry_dataview (arraybuffer, 0, 16);
  jerry_length_t byteOffset = 0;
  jerry_length_t byteLength = 0;
  jerry_value_t buffer = jerry_dataview_buffer (dataview, &byteOffset, &byteLength);

  // buffer is an ArrayBuffer object and ArrayBuffer operations can be performed on it
  // byteOffset is 0
  // byteLength is 16

  // usage of buffer

  jerry_value_free (buffer);
  jerry_value_free (dataview);
  jerry_value_free (arraybuffer);

  jerry_cleanup ();
}

See also

jerry_typedarray_type

Summary

Get the type of the TypedArray.

The returned type is one of the jerry_typedarray_type_t enum value.

Prototype

jerry_typedarray_type_t
jerry_typedarray_type (jerry_value_t value);
  • value - TypedArray object to query for type.
  • return
    • the type of the TypedArray
    • JERRY_TYPEDARRAY_INVALID if the object was not a TypedArray

New in version 2.0.

Example

{
  jerry_typedarray_type_t expected_type = JERRY_TYPEDARRAY_UINT32;
  jerry_value_t typedarray = jerry_typedarray (expected_class, 25);

  jerry_typedarray_type_t type = jerry_typedarray_type (typedarray);

  // 'type' is now JERRY_TYPEDARRAY_UINT32

  jerry_value_free (typedarray);
}

See also

jerry_typedarray_length

Summary

Get the element count of the TypedArray as specified during creation.

This is not the same as the byteLength property of a TypedArray object.

Prototype

jerry_length_t
jerry_typedarray_length (jerry_value_t value);
  • value - TypedArray object to query
  • return
    • length (element count) of the TypedArray object
    • 0 if the object is not a TypedArray

New in version 2.0.

Example

{
  jerry_value_t array = jerry_typedarray (JERRY_TYPEDARRAY_INT32, 21);

  jerry_length_t element_count = jerry_typedarray_length (array);

  // element_count is now 21.

  jerry_value_free (array);
}

See also

jerry_typedarray_buffer

Summary

Get the ArrayBuffer object used by a TypedArray object. Additionally returns the byteLength and byteOffset properties of the TypedArray object.

For the returned ArrayBuffer the jerry_value_free must be called.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_typedarray_buffer (jerry_value_t value,
                         jerry_length_t *byteOffset,
                         jerry_length_t *byteLength);
  • value - TypedArray to get the ArrayBuffer from
  • byteOffset - (Optional) returns the start offset of the ArrayBuffer for the TypedArray
  • byteLength - (Optional) returns the number of bytes used from the ArrayBuffer for the TypedArray
  • return
    • TypedArray object’s underlying ArrayBuffer object
    • TypeError if the value is not a TypedArray object

New in version 2.0.

Example

{
  jerry_value_t array = jerry_typedarray (JERRY_TYPEDARRAY_INT16, 11);

  jerry_length_t byteLength = 0;
  jerry_length_t byteOffset = 0;
  jerry_value_t buffer = jerry_typedarray_buffer (array, &byteOffset, &byteLength);

  // buffer is an ArrayBuffer object and ArrayBuffer operations can be performed on it
  // byteLength is 11 * 2 (2 as the TypedArray stores Int16 that is 2 byte elements)
  // byteOffset is 0

  jerry_value_free (buffer);
  jerry_value_free (array);
}

See also

JSON functions

jerry_json_parse

Summary

Parses a CESU-8 or UTF-8 encoded string as a JSON string, creating a JavaScript value. The behaviour is equivalent with the “JSON.parse(string)” JS call.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_json_parse (const jerry_char_t *string_p,
                  jerry_size_t string_size);
  • string_p - pointer to a JSON string.
  • string_size - size of the string.
  • return
    • jerry_value_t containing a JavaScript value.
    • exception value in case of any parse error.

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  /* Initialize engine */
  jerry_init (JERRY_INIT_EMPTY);

  const jerry_char_t data[] = "{\"name\": \"John\", \"age\": 5}";
  jerry_value_t obj = jerry_json_parse (data, sizeof (data) - 1);

  /* "obj" now contains and object created from the "data" JSON string. */

  jerry_value_free (obj);

  /* Cleanup engine */
  jerry_cleanup ();

  return 0;
}

jerry_json_stringify

Summary

Create a JSON string value from a JavaScript value. The behaviour is equivalent with the “JSON.stringify(input_value)” JS call.

Note: Returned value must be freed with jerry_value_free when it is no longer needed.

Prototype

jerry_value_t
jerry_json_stringify (const jerry_value_t input_value);
  • input_value - a jerry_value_t to stringify.
  • return
    • jerry_value_t containing a JSON string.
    • exception value in case of any stringification error.

New in version 2.0.

Example

#include "jerryscript.h"

int
main (void)
{
  /* Initialize engine */
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t obj = jerry_object ();
  {
    jerry_value_t key = jerry_string_sz ("name");
    jerry_value_t value = jerry_string_sz ("John");
    jerry_value_free (jerry_object_set (obj, key, value));
    jerry_value_free (key);
    jerry_value_free (value);
  }

  jerry_value_t stringified = jerry_json_stringify (obj);

  /* "stringified" now contains a JSON string */

  jerry_value_free (stringified);
  jerry_value_free (obj);

  /* Cleanup engine */
  jerry_cleanup ();

  return 0;
}

Container Functions

jerry_container_to_array

Summary

Return a new array containing elements from a Container, or a Container Iterator. Sets the is_key_value_p to true. if the container object contains key-value structure and false if not.

Notes

  • The return value will be an empty array if the Map/Set or Iterator object was empty or finished.
  • This API function depends on a build option (JERRY_BUILTIN_CONTAINER) and can be checked runtime with the JERRY_FEATURE_MAP, JERRY_FEATURE_SET, JERRY_FEATURE_WEAKMAP, JERRY_FEATURE_WEAKSET feature enum values. see: jerry_feature_enabled.
  • The es.next profile enables this by default.

New in version [[NEXT_RELEASE]].

Prototype

jerry_value_t
jerry_container_to_array(jerry_value_t value,
                         bool *is_key_value_p);
  • value - Map/Set or iterator object
  • is_key_value - Will be set to true if the given container has key-value pairs, false otherwise.
  • return value
    • jerry_value_t containing an array of values from the Map/Set or iterator object
    • exception if the value is nor a Container or a Container Iterator.
    • undefined if the value is undefined/null. Example
#include "jerryscript.h"
int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_char_t src[] = "var map = new Map(); map.set(1,2); map.entries()";
  jerry_value_t iterable = jerry_eval (src, sizeof (src) - 1, JERRY_PARSE_NO_OPTS);

  bool is_key_value_container = false;
  jerry_value_t buffer_from_map = jerry_container_to_array (iterable, &is_key_value_container);

  /*
    The buffer_from_map contains two elements: 1 and 2, which is the key/value pair of the only item in the set.
    is_key_value set to true, as the original is a key-value structure (a Map Iterator)
  */

  jerry_value_free (iterable);
  jerry_value_free (buffer_from_map);

  jerry_cleanup ();

  return 0;
}

See also

jerry_container_op

Summary

Perform container operation on the given operands (add, delete, set, etc.).

Note:

  • Returned value must be freed with jerry_value_free when it is no longer needed.
  • This API function depends on a build option (JERRY_BUILTIN_CONTAINER) and can be checked runtime with the JERRY_FEATURE_MAP , JERRY_FEATURE_SET , JERRY_FEATURE_WEAKMAP , JERRY_FEATURE_WEAKSET feature enum values. see: jerry_feature_enabled.
  • The es.next profile enables this by default.

Prototype

jerry_value_t
jerry_container_op (jerry_container_op_t operation,
                    jerry_value_t container,
                    jerry_value_t *arguments,
                    uint32_t arguments_number)
  • operation - container operation
  • container - this value
  • arguments - array of arguments
  • arguments_number - number of arguments
  • result if the operation is successful
  • exception, otherwise

New in version [[NEXT_RELEASE]].

Example

#include "jerryscript.h"

int
main (void)
{
  jerry_init (JERRY_INIT_EMPTY);

  jerry_value_t map = jerry_container (JERRY_CONTAINER_TYPE_MAP, NULL, 0);
  jerry_value_t key_str = jerry_string_sz ("number");
  jerry_value_t number = jerry_number (10);
  jerry_value_t args[2] = {key_str, number};

  jerry_value_t result = jerry_container_op (JERRY_CONTAINER_OP_SET, map, args, 2);
  jerry_value_free (result);

  result = jerry_container_op (JERRY_CONTAINER_OP_SIZE, map, NULL, 0);
  jerry_value_free (result);

  result = jerry_container_op (JERRY_CONTAINER_OP_CLEAR, map, NULL, 0);
  jerry_value_free (result);

  jerry_value_free (map);
  jerry_value_free (key_str);
  jerry_value_free (number);

  jerry_cleanup ();
  return 0;
}

See also