{ "type": "module", "source": "doc/api/n-api.md", "introduced_in": "v8.0.0", "stability": 2, "stabilityText": "Stable", "miscs": [ { "textRaw": "N-API", "name": "N-API", "introduced_in": "v8.0.0", "type": "misc", "stability": 2, "stabilityText": "Stable", "desc": "

N-API (pronounced N as in the letter, followed by API)\nis an API for building native Addons. It is independent from\nthe underlying JavaScript runtime (for example, V8) and is maintained as part of\nNode.js itself. This API will be Application Binary Interface (ABI) stable\nacross versions of Node.js. It is intended to insulate Addons from\nchanges in the underlying JavaScript engine and allow modules\ncompiled for one major version to run on later major versions of Node.js without\nrecompilation. The ABI Stability guide provides a more in-depth explanation.

\n

Addons are built/packaged with the same approach/tools outlined in the section\ntitled C++ Addons. The only difference is the set of APIs that are used by\nthe native code. Instead of using the V8 or Native Abstractions for Node.js\nAPIs, the functions available in the N-API are used.

\n

APIs exposed by N-API are generally used to create and manipulate\nJavaScript values. Concepts and operations generally map to ideas specified\nin the ECMA-262 Language Specification. The APIs have the following\nproperties:

\n\n

The N-API is a C API that ensures ABI stability across Node.js versions\nand different compiler levels. A C++ API can be easier to use.\nTo support using C++, the project maintains a\nC++ wrapper module called node-addon-api.\nThis wrapper provides an inlineable C++ API. Binaries built\nwith node-addon-api will depend on the symbols for the N-API C-based\nfunctions exported by Node.js. node-addon-api is a more\nefficient way to write code that calls N-API. Take, for example, the\nfollowing node-addon-api code. The first section shows the\nnode-addon-api code and the second section shows what actually gets\nused in the addon.

\n
Object obj = Object::New(env);\nobj[\"foo\"] = String::New(env, \"bar\");\n
\n
napi_status status;\nnapi_value object, string;\nstatus = napi_create_object(env, &object);\nif (status != napi_ok) {\n  napi_throw_error(env, ...);\n  return;\n}\n\nstatus = napi_create_string_utf8(env, \"bar\", NAPI_AUTO_LENGTH, &string);\nif (status != napi_ok) {\n  napi_throw_error(env, ...);\n  return;\n}\n\nstatus = napi_set_named_property(env, object, \"foo\", string);\nif (status != napi_ok) {\n  napi_throw_error(env, ...);\n  return;\n}\n
\n

The end result is that the addon only uses the exported C APIs. As a result,\nit still gets the benefits of the ABI stability provided by the C API.

\n

When using node-addon-api instead of the C APIs, start with the API docs\nfor node-addon-api.

", "miscs": [ { "textRaw": "Implications of ABI stability", "name": "implications_of_abi_stability", "desc": "

Although N-API provides an ABI stability guarantee, other parts of Node.js do\nnot, and any external libraries used from the addon may not. In particular,\nnone of the following APIs provide an ABI stability guarantee across major\nversions:

\n\n

Thus, for an addon to remain ABI-compatible across Node.js major versions, it\nmust make use exclusively of N-API by restricting itself to using

\n
#include <node_api.h>\n
\n

and by checking, for all external libraries that it uses, that the external\nlibrary makes ABI stability guarantees similar to N-API.

", "type": "misc", "displayName": "Implications of ABI stability" }, { "textRaw": "Building", "name": "building", "desc": "

Unlike modules written in JavaScript, developing and deploying Node.js\nnative addons using N-API requires an additional set of tools. Besides the\nbasic tools required to develop for Node.js, the native addon developer\nrequires a toolchain that can compile C and C++ code into a binary. In\naddition, depending upon how the native addon is deployed, the user of\nthe native addon will also need to have a C/C++ toolchain installed.

\n

For Linux developers, the necessary C/C++ toolchain packages are readily\navailable. GCC is widely used in the Node.js community to build and\ntest across a variety of platforms. For many developers, the LLVM\ncompiler infrastructure is also a good choice.

\n

For Mac developers, Xcode offers all the required compiler tools.\nHowever, it is not necessary to install the entire Xcode IDE. The following\ncommand installs the necessary toolchain:

\n
xcode-select --install\n
\n

For Windows developers, Visual Studio offers all the required compiler\ntools. However, it is not necessary to install the entire Visual Studio\nIDE. The following command installs the necessary toolchain:

\n
npm install --global --production windows-build-tools\n
\n

The sections below describe the additional tools available for developing\nand deploying Node.js native addons.

", "modules": [ { "textRaw": "Build tools", "name": "build_tools", "desc": "

Both the tools listed here require that users of the native\naddon have a C/C++ toolchain installed in order to successfully install\nthe native addon.

", "modules": [ { "textRaw": "node-gyp", "name": "node-gyp", "desc": "

node-gyp is a build system based on Google's GYP tool and comes\nbundled with npm. GYP, and therefore node-gyp, requires that Python be\ninstalled.

\n

Historically, node-gyp has been the tool of choice for building native\naddons. It has widespread adoption and documentation. However, some\ndevelopers have run into limitations in node-gyp.

", "type": "module", "displayName": "node-gyp" } ], "properties": [ { "textRaw": "CMake.js", "name": "js", "desc": "

CMake.js is an alternative build system based on CMake.

\n

CMake.js is a good choice for projects that already use CMake or for\ndevelopers affected by limitations in node-gyp.

" } ], "type": "module", "displayName": "Build tools" }, { "textRaw": "Uploading precompiled binaries", "name": "uploading_precompiled_binaries", "desc": "

The three tools listed here permit native addon developers and maintainers\nto create and upload binaries to public or private servers. These tools are\ntypically integrated with CI/CD build systems like Travis CI and\nAppVeyor to build and upload binaries for a variety of platforms and\narchitectures. These binaries are then available for download by users who\ndo not need to have a C/C++ toolchain installed.

", "modules": [ { "textRaw": "node-pre-gyp", "name": "node-pre-gyp", "desc": "

node-pre-gyp is a tool based on node-gyp that adds the ability to\nupload binaries to a server of the developer's choice. node-pre-gyp has\nparticularly good support for uploading binaries to Amazon S3.

", "type": "module", "displayName": "node-pre-gyp" }, { "textRaw": "prebuild", "name": "prebuild", "desc": "

prebuild is a tool that supports builds using either node-gyp or\nCMake.js. Unlike node-pre-gyp which supports a variety of servers, prebuild\nuploads binaries only to GitHub releases. prebuild is a good choice for\nGitHub projects using CMake.js.

", "type": "module", "displayName": "prebuild" }, { "textRaw": "prebuildify", "name": "prebuildify", "desc": "

prebuildify is a tool based on node-gyp. The advantage of prebuildify is\nthat the built binaries are bundled with the native module when it's\nuploaded to npm. The binaries are downloaded from npm and are immediately\navailable to the module user when the native module is installed.

", "type": "module", "displayName": "prebuildify" } ], "type": "module", "displayName": "Uploading precompiled binaries" } ], "type": "misc", "displayName": "Building" }, { "textRaw": "Usage", "name": "usage", "desc": "

In order to use the N-API functions, include the file node_api.h which is\nlocated in the src directory in the node development tree:

\n
#include <node_api.h>\n
\n

This will opt into the default NAPI_VERSION for the given release of Node.js.\nIn order to ensure compatibility with specific versions of N-API, the version\ncan be specified explicitly when including the header:

\n
#define NAPI_VERSION 3\n#include <node_api.h>\n
\n

This restricts the N-API surface to just the functionality that was available in\nthe specified (and earlier) versions.

\n

Some of the N-API surface is experimental and requires explicit opt-in:

\n
#define NAPI_EXPERIMENTAL\n#include <node_api.h>\n
\n

In this case the entire API surface, including any experimental APIs, will be\navailable to the module code.

", "type": "misc", "displayName": "Usage" }, { "textRaw": "N-API version matrix", "name": "n-api_version_matrix", "desc": "

N-API versions are additive and versioned independently from Node.js.\nVersion 4 is an extension to version 3 in that it has all of the APIs\nfrom version 3 with some additions. This means that it is not necessary\nto recompile for new versions of Node.js which are\nlisted as supporting a later version.

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
123456
v6.xv6.14.2*
v8.xv8.0.0*v8.10.0*v8.11.2v8.16.0
v9.xv9.0.0*v9.3.0*v9.11.0*
v10.xv10.0.0v10.0.0v10.0.0v10.16.0v10.17.0v10.20.0
v11.xv11.0.0v11.0.0v11.0.0v11.8.0
v12.xv12.0.0v12.0.0v12.0.0v12.0.0v12.11.0
v13.xv13.0.0v13.0.0v13.0.0v13.0.0v13.0.0
v14.xv14.0.0v14.0.0v14.0.0v14.0.0v14.0.0v14.0.0
\n

* Indicates that the N-API version was released as experimental

\n

The N-APIs associated strictly with accessing ECMAScript features from native\ncode can be found separately in js_native_api.h and js_native_api_types.h.\nThe APIs defined in these headers are included in node_api.h and\nnode_api_types.h. The headers are structured in this way in order to allow\nimplementations of N-API outside of Node.js. For those implementations the\nNode.js specific APIs may not be applicable.

\n

The Node.js-specific parts of an addon can be separated from the code that\nexposes the actual functionality to the JavaScript environment so that the\nlatter may be used with multiple implementations of N-API. In the example below,\naddon.c and addon.h refer only to js_native_api.h. This ensures that\naddon.c can be reused to compile against either the Node.js implementation of\nN-API or any implementation of N-API outside of Node.js.

\n

addon_node.c is a separate file that contains the Node.js specific entry point\nto the addon and which instantiates the addon by calling into addon.c when the\naddon is loaded into a Node.js environment.

\n
// addon.h\n#ifndef _ADDON_H_\n#define _ADDON_H_\n#include <js_native_api.h>\nnapi_value create_addon(napi_env env);\n#endif  // _ADDON_H_\n
\n
// addon.c\n#include \"addon.h\"\n\n#define NAPI_CALL(env, call)                                      \\\n  do {                                                            \\\n    napi_status status = (call);                                  \\\n    if (status != napi_ok) {                                      \\\n      const napi_extended_error_info* error_info = NULL;          \\\n      napi_get_last_error_info((env), &error_info);               \\\n      bool is_pending;                                            \\\n      napi_is_exception_pending((env), &is_pending);              \\\n      if (!is_pending) {                                          \\\n        const char* message = (error_info->error_message == NULL) \\\n            ? \"empty error message\"                               \\\n            : error_info->error_message;                          \\\n        napi_throw_error((env), NULL, message);                   \\\n        return NULL;                                              \\\n      }                                                           \\\n    }                                                             \\\n  } while(0)\n\nstatic napi_value\nDoSomethingUseful(napi_env env, napi_callback_info info) {\n  // Do something useful.\n  return NULL;\n}\n\nnapi_value create_addon(napi_env env) {\n  napi_value result;\n  NAPI_CALL(env, napi_create_object(env, &result));\n\n  napi_value exported_function;\n  NAPI_CALL(env, napi_create_function(env,\n                                      \"doSomethingUseful\",\n                                      NAPI_AUTO_LENGTH,\n                                      DoSomethingUseful,\n                                      NULL,\n                                      &exported_function));\n\n  NAPI_CALL(env, napi_set_named_property(env,\n                                         result,\n                                         \"doSomethingUseful\",\n                                         exported_function));\n\n  return result;\n}\n
\n
// addon_node.c\n#include <node_api.h>\n#include \"addon.h\"\n\nNAPI_MODULE_INIT() {\n  // This function body is expected to return a `napi_value`.\n  // The variables `napi_env env` and `napi_value exports` may be used within\n  // the body, as they are provided by the definition of `NAPI_MODULE_INIT()`.\n  return create_addon(env);\n}\n
", "type": "misc", "displayName": "N-API version matrix" }, { "textRaw": "Environment life cycle APIs", "name": "environment_life_cycle_apis", "stability": 1, "stabilityText": "Experimental", "desc": "

Section 8.7 of the ECMAScript Language Specification defines the concept\nof an \"Agent\" as a self-contained environment in which JavaScript code runs.\nMultiple such Agents may be started and terminated either concurrently or in\nsequence by the process.

\n

A Node.js environment corresponds to an ECMAScript Agent. In the main process,\nan environment is created at startup, and additional environments can be created\non separate threads to serve as worker threads. When Node.js is embedded in\nanother application, the main thread of the application may also construct and\ndestroy a Node.js environment multiple times during the life cycle of the\napplication process such that each Node.js environment created by the\napplication may, in turn, during its life cycle create and destroy additional\nenvironments as worker threads.

\n

From the perspective of a native addon this means that the bindings it provides\nmay be called multiple times, from multiple contexts, and even concurrently from\nmultiple threads.

\n

Native addons may need to allocate global state of which they make use during\ntheir entire life cycle such that the state must be unique to each instance of\nthe addon.

\n

To this end, N-API provides a way to allocate data such that its life cycle is\ntied to the life cycle of the Agent.

", "modules": [ { "textRaw": "napi_set_instance_data", "name": "napi_set_instance_data", "meta": { "added": [ "v12.8.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_set_instance_data(napi_env env,\n                                   void* data,\n                                   napi_finalize finalize_cb,\n                                   void* finalize_hint);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API associates data with the currently running Agent. data can later\nbe retrieved using napi_get_instance_data(). Any existing data associated with\nthe currently running Agent which was set by means of a previous call to\nnapi_set_instance_data() will be overwritten. If a finalize_cb was provided\nby the previous call, it will not be called.

", "type": "module", "displayName": "napi_set_instance_data" }, { "textRaw": "napi_get_instance_data", "name": "napi_get_instance_data", "meta": { "added": [ "v12.8.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_get_instance_data(napi_env env,\n                                   void** data);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API retrieves data that was previously associated with the currently\nrunning Agent via napi_set_instance_data(). If no data is set, the call will\nsucceed and data will be set to NULL.

", "type": "module", "displayName": "napi_get_instance_data" } ], "type": "misc", "displayName": "Environment life cycle APIs" }, { "textRaw": "Basic N-API data types", "name": "basic_n-api_data_types", "desc": "

N-API exposes the following fundamental datatypes as abstractions that are\nconsumed by the various APIs. These APIs should be treated as opaque,\nintrospectable only with other N-API calls.

", "modules": [ { "textRaw": "napi_status", "name": "napi_status", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Integral status code indicating the success or failure of a N-API call.\nCurrently, the following status codes are supported.

\n
typedef enum {\n  napi_ok,\n  napi_invalid_arg,\n  napi_object_expected,\n  napi_string_expected,\n  napi_name_expected,\n  napi_function_expected,\n  napi_number_expected,\n  napi_boolean_expected,\n  napi_array_expected,\n  napi_generic_failure,\n  napi_pending_exception,\n  napi_cancelled,\n  napi_escape_called_twice,\n  napi_handle_scope_mismatch,\n  napi_callback_scope_mismatch,\n  napi_queue_full,\n  napi_closing,\n  napi_bigint_expected,\n  napi_date_expected,\n  napi_arraybuffer_expected,\n  napi_detachable_arraybuffer_expected,\n  napi_would_deadlock,  /* unused */\n} napi_status;\n
\n

If additional information is required upon an API returning a failed status,\nit can be obtained by calling napi_get_last_error_info.

", "type": "module", "displayName": "napi_status" }, { "textRaw": "napi_extended_error_info", "name": "napi_extended_error_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
typedef struct {\n  const char* error_message;\n  void* engine_reserved;\n  uint32_t engine_error_code;\n  napi_status error_code;\n} napi_extended_error_info;\n
\n\n

See the Error handling section for additional information.

", "type": "module", "displayName": "napi_extended_error_info" }, { "textRaw": "napi_env", "name": "napi_env", "desc": "

napi_env is used to represent a context that the underlying N-API\nimplementation can use to persist VM-specific state. This structure is passed\nto native functions when they're invoked, and it must be passed back when\nmaking N-API calls. Specifically, the same napi_env that was passed in when\nthe initial native function was called must be passed to any subsequent\nnested N-API calls. Caching the napi_env for the purpose of general reuse,\nand passing the napi_env between instances of the same addon running on\ndifferent Worker threads is not allowed. The napi_env becomes invalid\nwhen an instance of a native addon is unloaded. Notification of this event is\ndelivered through the callbacks given to napi_add_env_cleanup_hook and\nnapi_set_instance_data.

", "type": "module", "displayName": "napi_env" }, { "textRaw": "napi_value", "name": "napi_value", "desc": "

This is an opaque pointer that is used to represent a JavaScript value.

", "type": "module", "displayName": "napi_value" }, { "textRaw": "napi_threadsafe_function", "name": "napi_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "

This is an opaque pointer that represents a JavaScript function which can be\ncalled asynchronously from multiple threads via\nnapi_call_threadsafe_function().

", "type": "module", "displayName": "napi_threadsafe_function" }, { "textRaw": "napi_threadsafe_function_release_mode", "name": "napi_threadsafe_function_release_mode", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "

A value to be given to napi_release_threadsafe_function() to indicate whether\nthe thread-safe function is to be closed immediately (napi_tsfn_abort) or\nmerely released (napi_tsfn_release) and thus available for subsequent use via\nnapi_acquire_threadsafe_function() and napi_call_threadsafe_function().

\n
typedef enum {\n  napi_tsfn_release,\n  napi_tsfn_abort\n} napi_threadsafe_function_release_mode;\n
", "type": "module", "displayName": "napi_threadsafe_function_release_mode" }, { "textRaw": "napi_threadsafe_function_call_mode", "name": "napi_threadsafe_function_call_mode", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "

A value to be given to napi_call_threadsafe_function() to indicate whether\nthe call should block whenever the queue associated with the thread-safe\nfunction is full.

\n
typedef enum {\n  napi_tsfn_nonblocking,\n  napi_tsfn_blocking\n} napi_threadsafe_function_call_mode;\n
", "type": "module", "displayName": "napi_threadsafe_function_call_mode" }, { "textRaw": "N-API memory management types", "name": "n-api_memory_management_types", "modules": [ { "textRaw": "napi_handle_scope", "name": "napi_handle_scope", "desc": "

This is an abstraction used to control and modify the lifetime of objects\ncreated within a particular scope. In general, N-API values are created within\nthe context of a handle scope. When a native method is called from\nJavaScript, a default handle scope will exist. If the user does not explicitly\ncreate a new handle scope, N-API values will be created in the default handle\nscope. For any invocations of code outside the execution of a native method\n(for instance, during a libuv callback invocation), the module is required to\ncreate a scope before invoking any functions that can result in the creation\nof JavaScript values.

\n

Handle scopes are created using napi_open_handle_scope and are destroyed\nusing napi_close_handle_scope. Closing the scope can indicate to the GC\nthat all napi_values created during the lifetime of the handle scope are no\nlonger referenced from the current stack frame.

\n

For more details, review the Object lifetime management.

", "type": "module", "displayName": "napi_handle_scope" }, { "textRaw": "napi_escapable_handle_scope", "name": "napi_escapable_handle_scope", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Escapable handle scopes are a special type of handle scope to return values\ncreated within a particular handle scope to a parent scope.

", "type": "module", "displayName": "napi_escapable_handle_scope" }, { "textRaw": "napi_ref", "name": "napi_ref", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

This is the abstraction to use to reference a napi_value. This allows for\nusers to manage the lifetimes of JavaScript values, including defining their\nminimum lifetimes explicitly.

\n

For more details, review the Object lifetime management.

", "type": "module", "displayName": "napi_ref" } ], "type": "module", "displayName": "N-API memory management types" }, { "textRaw": "N-API callback types", "name": "n-api_callback_types", "modules": [ { "textRaw": "napi_callback_info", "name": "napi_callback_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Opaque datatype that is passed to a callback function. It can be used for\ngetting additional information about the context in which the callback was\ninvoked.

", "type": "module", "displayName": "napi_callback_info" }, { "textRaw": "napi_callback", "name": "napi_callback", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Function pointer type for user-provided native functions which are to be\nexposed to JavaScript via N-API. Callback functions should satisfy the\nfollowing signature:

\n
typedef napi_value (*napi_callback)(napi_env, napi_callback_info);\n
\n

Unless for reasons discussed in Object Lifetime Management, creating a\nhandle and/or callback scope inside a napi_callback is not necessary.

", "type": "module", "displayName": "napi_callback" }, { "textRaw": "napi_finalize", "name": "napi_finalize", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Function pointer type for add-on provided functions that allow the user to be\nnotified when externally-owned data is ready to be cleaned up because the\nobject with which it was associated with, has been garbage-collected. The user\nmust provide a function satisfying the following signature which would get\ncalled upon the object's collection. Currently, napi_finalize can be used for\nfinding out when objects that have external data are collected.

\n
typedef void (*napi_finalize)(napi_env env,\n                              void* finalize_data,\n                              void* finalize_hint);\n
\n

Unless for reasons discussed in Object Lifetime Management, creating a\nhandle and/or callback scope inside the function body is not necessary.

", "type": "module", "displayName": "napi_finalize" }, { "textRaw": "napi_async_execute_callback", "name": "napi_async_execute_callback", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Function pointer used with functions that support asynchronous\noperations. Callback functions must satisfy the following signature:

\n
typedef void (*napi_async_execute_callback)(napi_env env, void* data);\n
\n

Implementations of this function must avoid making N-API calls that execute\nJavaScript or interact with JavaScript objects. N-API calls should be in the\nnapi_async_complete_callback instead. Do not use the napi_env parameter as\nit will likely result in execution of JavaScript.

", "type": "module", "displayName": "napi_async_execute_callback" }, { "textRaw": "napi_async_complete_callback", "name": "napi_async_complete_callback", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

Function pointer used with functions that support asynchronous\noperations. Callback functions must satisfy the following signature:

\n
typedef void (*napi_async_complete_callback)(napi_env env,\n                                             napi_status status,\n                                             void* data);\n
\n

Unless for reasons discussed in Object Lifetime Management, creating a\nhandle and/or callback scope inside the function body is not necessary.

", "type": "module", "displayName": "napi_async_complete_callback" }, { "textRaw": "napi_threadsafe_function_call_js", "name": "napi_threadsafe_function_call_js", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "

Function pointer used with asynchronous thread-safe function calls. The callback\nwill be called on the main thread. Its purpose is to use a data item arriving\nvia the queue from one of the secondary threads to construct the parameters\nnecessary for a call into JavaScript, usually via napi_call_function, and then\nmake the call into JavaScript.

\n

The data arriving from the secondary thread via the queue is given in the data\nparameter and the JavaScript function to call is given in the js_callback\nparameter.

\n

N-API sets up the environment prior to calling this callback, so it is\nsufficient to call the JavaScript function via napi_call_function rather than\nvia napi_make_callback.

\n

Callback functions must satisfy the following signature:

\n
typedef void (*napi_threadsafe_function_call_js)(napi_env env,\n                                                 napi_value js_callback,\n                                                 void* context,\n                                                 void* data);\n
\n\n

Unless for reasons discussed in Object Lifetime Management, creating a\nhandle and/or callback scope inside the function body is not necessary.

", "type": "module", "displayName": "napi_threadsafe_function_call_js" } ], "type": "module", "displayName": "N-API callback types" } ], "type": "misc", "displayName": "Basic N-API data types" }, { "textRaw": "Error handling", "name": "error_handling", "desc": "

N-API uses both return values and JavaScript exceptions for error handling.\nThe following sections explain the approach for each case.

", "modules": [ { "textRaw": "Return values", "name": "return_values", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "

All of the N-API functions share the same error handling pattern. The\nreturn type of all API functions is napi_status.

\n

The return value will be napi_ok if the request was successful and\nno uncaught JavaScript exception was thrown. If an error occurred AND\nan exception was thrown, the napi_status value for the error\nwill be returned. If an exception was thrown, and no error occurred,\nnapi_pending_exception will be returned.

\n

In cases where a return value other than napi_ok or\nnapi_pending_exception is returned, napi_is_exception_pending\nmust be called to check if an exception is pending.\nSee the section on exceptions for more details.

\n

The full set of possible napi_status values is defined\nin napi_api_types.h.

\n

The napi_status return value provides a VM-independent representation of\nthe error which occurred. In some cases it is useful to be able to get\nmore detailed information, including a string representing the error as well as\nVM (engine)-specific information.

\n

In order to retrieve this information napi_get_last_error_info\nis provided which returns a napi_extended_error_info structure.\nThe format of the napi_extended_error_info structure is as follows:

\n
typedef struct napi_extended_error_info {\n  const char* error_message;\n  void* engine_reserved;\n  uint32_t engine_error_code;\n  napi_status error_code;\n};\n
\n\n

napi_get_last_error_info returns the information for the last\nN-API call that was made.

\n

Do not rely on the content or format of any of the extended information as it\nis not subject to SemVer and may change at any time. It is intended only for\nlogging purposes.

", "modules": [ { "textRaw": "napi_get_last_error_info", "name": "napi_get_last_error_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status\nnapi_get_last_error_info(napi_env env,\n                         const napi_extended_error_info** result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API retrieves a napi_extended_error_info structure with information\nabout the last error that occurred.

\n

The content of the napi_extended_error_info returned is only valid up until\nan n-api function is called on the same env.

\n

Do not rely on the content or format of any of the extended information as it\nis not subject to SemVer and may change at any time. It is intended only for\nlogging purposes.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_get_last_error_info" } ], "type": "module", "displayName": "Return values" }, { "textRaw": "Exceptions", "name": "exceptions", "desc": "

Any N-API function call may result in a pending JavaScript exception. This is\nthe case for any of the API functions, even those that may not cause the\nexecution of JavaScript.

\n

If the napi_status returned by a function is napi_ok then no\nexception is pending and no additional action is required. If the\nnapi_status returned is anything other than napi_ok or\nnapi_pending_exception, in order to try to recover and continue\ninstead of simply returning immediately, napi_is_exception_pending\nmust be called in order to determine if an exception is pending or not.

\n

In many cases when an N-API function is called and an exception is\nalready pending, the function will return immediately with a\nnapi_status of napi_pending_exception. However, this is not the case\nfor all functions. N-API allows a subset of the functions to be\ncalled to allow for some minimal cleanup before returning to JavaScript.\nIn that case, napi_status will reflect the status for the function. It\nwill not reflect previous pending exceptions. To avoid confusion, check\nthe error status after every function call.

\n

When an exception is pending one of two approaches can be employed.

\n

The first approach is to do any appropriate cleanup and then return so that\nexecution will return to JavaScript. As part of the transition back to\nJavaScript, the exception will be thrown at the point in the JavaScript\ncode where the native method was invoked. The behavior of most N-API calls\nis unspecified while an exception is pending, and many will simply return\nnapi_pending_exception, so do as little as possible and then return to\nJavaScript where the exception can be handled.

\n

The second approach is to try to handle the exception. There will be cases\nwhere the native code can catch the exception, take the appropriate action,\nand then continue. This is only recommended in specific cases\nwhere it is known that the exception can be safely handled. In these\ncases napi_get_and_clear_last_exception can be used to get and\nclear the exception. On success, result will contain the handle to\nthe last JavaScript Object thrown. If it is determined, after\nretrieving the exception, the exception cannot be handled after all\nit can be re-thrown it with napi_throw where error is the\nJavaScript Error object to be thrown.

\n

The following utility functions are also available in case native code\nneeds to throw an exception or determine if a napi_value is an instance\nof a JavaScript Error object: napi_throw_error,\nnapi_throw_type_error, napi_throw_range_error and\nnapi_is_error.

\n

The following utility functions are also available in case native\ncode needs to create an Error object: napi_create_error,\nnapi_create_type_error, and napi_create_range_error,\nwhere result is the napi_value that refers to the newly created\nJavaScript Error object.

\n

The Node.js project is adding error codes to all of the errors\ngenerated internally. The goal is for applications to use these\nerror codes for all error checking. The associated error messages\nwill remain, but will only be meant to be used for logging and\ndisplay with the expectation that the message can change without\nSemVer applying. In order to support this model with N-API, both\nin internal functionality and for module specific functionality\n(as its good practice), the throw_ and create_ functions\ntake an optional code parameter which is the string for the code\nto be added to the error object. If the optional parameter is NULL\nthen no code will be associated with the error. If a code is provided,\nthe name associated with the error is also updated to be:

\n
originalName [code]\n
\n

where originalName is the original name associated with the error\nand code is the code that was provided. For example, if the code\nis 'ERR_ERROR_1' and a TypeError is being created the name will be:

\n
TypeError [ERR_ERROR_1]\n
", "modules": [ { "textRaw": "napi_throw", "name": "napi_throw", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_throw(napi_env env, napi_value error);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API throws the JavaScript value provided.

", "type": "module", "displayName": "napi_throw" }, { "textRaw": "napi_throw_error", "name": "napi_throw_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_throw_error(napi_env env,\n                                         const char* code,\n                                         const char* msg);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API throws a JavaScript Error with the text provided.

", "type": "module", "displayName": "napi_throw_error" }, { "textRaw": "napi_throw_type_error", "name": "napi_throw_type_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_throw_type_error(napi_env env,\n                                              const char* code,\n                                              const char* msg);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API throws a JavaScript TypeError with the text provided.

", "type": "module", "displayName": "napi_throw_type_error" }, { "textRaw": "napi_throw_range_error", "name": "napi_throw_range_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_throw_range_error(napi_env env,\n                                               const char* code,\n                                               const char* msg);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API throws a JavaScript RangeError with the text provided.

", "type": "module", "displayName": "napi_throw_range_error" }, { "textRaw": "napi_is_error", "name": "napi_is_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_is_error(napi_env env,\n                                      napi_value value,\n                                      bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API queries a napi_value to check if it represents an error object.

", "type": "module", "displayName": "napi_is_error" }, { "textRaw": "napi_create_error", "name": "napi_create_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_create_error(napi_env env,\n                                          napi_value code,\n                                          napi_value msg,\n                                          napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns a JavaScript Error with the text provided.

", "type": "module", "displayName": "napi_create_error" }, { "textRaw": "napi_create_type_error", "name": "napi_create_type_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_create_type_error(napi_env env,\n                                               napi_value code,\n                                               napi_value msg,\n                                               napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns a JavaScript TypeError with the text provided.

", "type": "module", "displayName": "napi_create_type_error" }, { "textRaw": "napi_create_range_error", "name": "napi_create_range_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_create_range_error(napi_env env,\n                                                napi_value code,\n                                                napi_value msg,\n                                                napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns a JavaScript RangeError with the text provided.

", "type": "module", "displayName": "napi_create_range_error" }, { "textRaw": "napi_get_and_clear_last_exception", "name": "napi_get_and_clear_last_exception", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_and_clear_last_exception(napi_env env,\n                                              napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_get_and_clear_last_exception" }, { "textRaw": "napi_is_exception_pending", "name": "napi_is_exception_pending", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_exception_pending(napi_env env, bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_is_exception_pending" }, { "textRaw": "napi_fatal_exception", "name": "napi_fatal_exception", "meta": { "added": [ "v9.10.0" ], "napiVersion": [ 3 ], "changes": [] }, "desc": "
napi_status napi_fatal_exception(napi_env env, napi_value err);\n
\n\n

Trigger an 'uncaughtException' in JavaScript. Useful if an async\ncallback throws an exception with no way to recover.

", "type": "module", "displayName": "napi_fatal_exception" } ], "type": "module", "displayName": "Exceptions" }, { "textRaw": "Fatal errors", "name": "fatal_errors", "desc": "

In the event of an unrecoverable error in a native module, a fatal error can be\nthrown to immediately terminate the process.

", "modules": [ { "textRaw": "napi_fatal_error", "name": "napi_fatal_error", "meta": { "added": [ "v8.2.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_NO_RETURN void napi_fatal_error(const char* location,\n                                                 size_t location_len,\n                                                 const char* message,\n                                                 size_t message_len);\n
\n\n

The function call does not return, the process will be terminated.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_fatal_error" } ], "type": "module", "displayName": "Fatal errors" } ], "type": "misc", "displayName": "Error handling" }, { "textRaw": "Object lifetime management", "name": "object_lifetime_management", "desc": "

As N-API calls are made, handles to objects in the heap for the underlying\nVM may be returned as napi_values. These handles must hold the\nobjects 'live' until they are no longer required by the native code,\notherwise the objects could be collected before the native code was\nfinished using them.

\n

As object handles are returned they are associated with a\n'scope'. The lifespan for the default scope is tied to the lifespan\nof the native method call. The result is that, by default, handles\nremain valid and the objects associated with these handles will be\nheld live for the lifespan of the native method call.

\n

In many cases, however, it is necessary that the handles remain valid for\neither a shorter or longer lifespan than that of the native method.\nThe sections which follow describe the N-API functions that can be used\nto change the handle lifespan from the default.

", "modules": [ { "textRaw": "Making handle lifespan shorter than that of the native method", "name": "making_handle_lifespan_shorter_than_that_of_the_native_method", "desc": "

It is often necessary to make the lifespan of handles shorter than\nthe lifespan of a native method. For example, consider a native method\nthat has a loop which iterates through the elements in a large array:

\n
for (int i = 0; i < 1000000; i++) {\n  napi_value result;\n  napi_status status = napi_get_element(env, object, i, &result);\n  if (status != napi_ok) {\n    break;\n  }\n  // do something with element\n}\n
\n

This would result in a large number of handles being created, consuming\nsubstantial resources. In addition, even though the native code could only\nuse the most recent handle, all of the associated objects would also be\nkept alive since they all share the same scope.

\n

To handle this case, N-API provides the ability to establish a new 'scope' to\nwhich newly created handles will be associated. Once those handles\nare no longer required, the scope can be 'closed' and any handles associated\nwith the scope are invalidated. The methods available to open/close scopes are\nnapi_open_handle_scope and napi_close_handle_scope.

\n

N-API only supports a single nested hierarchy of scopes. There is only one\nactive scope at any time, and all new handles will be associated with that\nscope while it is active. Scopes must be closed in the reverse order from\nwhich they are opened. In addition, all scopes created within a native method\nmust be closed before returning from that method.

\n

Taking the earlier example, adding calls to napi_open_handle_scope and\nnapi_close_handle_scope would ensure that at most a single handle\nis valid throughout the execution of the loop:

\n
for (int i = 0; i < 1000000; i++) {\n  napi_handle_scope scope;\n  napi_status status = napi_open_handle_scope(env, &scope);\n  if (status != napi_ok) {\n    break;\n  }\n  napi_value result;\n  status = napi_get_element(env, object, i, &result);\n  if (status != napi_ok) {\n    break;\n  }\n  // do something with element\n  status = napi_close_handle_scope(env, scope);\n  if (status != napi_ok) {\n    break;\n  }\n}\n
\n

When nesting scopes, there are cases where a handle from an\ninner scope needs to live beyond the lifespan of that scope. N-API supports an\n'escapable scope' in order to support this case. An escapable scope\nallows one handle to be 'promoted' so that it 'escapes' the\ncurrent scope and the lifespan of the handle changes from the current\nscope to that of the outer scope.

\n

The methods available to open/close escapable scopes are\nnapi_open_escapable_handle_scope and\nnapi_close_escapable_handle_scope.

\n

The request to promote a handle is made through napi_escape_handle which\ncan only be called once.

", "modules": [ { "textRaw": "napi_open_handle_scope", "name": "napi_open_handle_scope", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_open_handle_scope(napi_env env,\n                                               napi_handle_scope* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API opens a new scope.

", "type": "module", "displayName": "napi_open_handle_scope" }, { "textRaw": "napi_close_handle_scope", "name": "napi_close_handle_scope", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_close_handle_scope(napi_env env,\n                                                napi_handle_scope scope);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API closes the scope passed in. Scopes must be closed in the\nreverse order from which they were created.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_close_handle_scope" }, { "textRaw": "napi_open_escapable_handle_scope", "name": "napi_open_escapable_handle_scope", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\n    napi_open_escapable_handle_scope(napi_env env,\n                                     napi_handle_scope* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API opens a new scope from which one object can be promoted\nto the outer scope.

", "type": "module", "displayName": "napi_open_escapable_handle_scope" }, { "textRaw": "napi_close_escapable_handle_scope", "name": "napi_close_escapable_handle_scope", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\n    napi_close_escapable_handle_scope(napi_env env,\n                                      napi_handle_scope scope);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API closes the scope passed in. Scopes must be closed in the\nreverse order from which they were created.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_close_escapable_handle_scope" }, { "textRaw": "napi_escape_handle", "name": "napi_escape_handle", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_escape_handle(napi_env env,\n                               napi_escapable_handle_scope scope,\n                               napi_value escapee,\n                               napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API promotes the handle to the JavaScript object so that it is valid\nfor the lifetime of the outer scope. It can only be called once per scope.\nIf it is called more than once an error will be returned.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_escape_handle" } ], "type": "module", "displayName": "Making handle lifespan shorter than that of the native method" }, { "textRaw": "References to objects with a lifespan longer than that of the native method", "name": "references_to_objects_with_a_lifespan_longer_than_that_of_the_native_method", "desc": "

In some cases an addon will need to be able to create and reference objects\nwith a lifespan longer than that of a single native method invocation. For\nexample, to create a constructor and later use that constructor\nin a request to creates instances, it must be possible to reference\nthe constructor object across many different instance creation requests. This\nwould not be possible with a normal handle returned as a napi_value as\ndescribed in the earlier section. The lifespan of a normal handle is\nmanaged by scopes and all scopes must be closed before the end of a native\nmethod.

\n

N-API provides methods to create persistent references to an object.\nEach persistent reference has an associated count with a value of 0\nor higher. The count determines if the reference will keep\nthe corresponding object live. References with a count of 0 do not\nprevent the object from being collected and are often called 'weak'\nreferences. Any count greater than 0 will prevent the object\nfrom being collected.

\n

References can be created with an initial reference count. The count can\nthen be modified through napi_reference_ref and\nnapi_reference_unref. If an object is collected while the count\nfor a reference is 0, all subsequent calls to\nget the object associated with the reference napi_get_reference_value\nwill return NULL for the returned napi_value. An attempt to call\nnapi_reference_ref for a reference whose object has been collected\nwill result in an error.

\n

References must be deleted once they are no longer required by the addon. When\na reference is deleted it will no longer prevent the corresponding object from\nbeing collected. Failure to delete a persistent reference will result in\na 'memory leak' with both the native memory for the persistent reference and\nthe corresponding object on the heap being retained forever.

\n

There can be multiple persistent references created which refer to the same\nobject, each of which will either keep the object live or not based on its\nindividual count.

", "modules": [ { "textRaw": "napi_create_reference", "name": "napi_create_reference", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_create_reference(napi_env env,\n                                              napi_value value,\n                                              uint32_t initial_refcount,\n                                              napi_ref* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API create a new reference with the specified reference count\nto the Object passed in.

", "type": "module", "displayName": "napi_create_reference" }, { "textRaw": "napi_delete_reference", "name": "napi_delete_reference", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_delete_reference(napi_env env, napi_ref ref);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API deletes the reference passed in.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_delete_reference" }, { "textRaw": "napi_reference_ref", "name": "napi_reference_ref", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_reference_ref(napi_env env,\n                                           napi_ref ref,\n                                           uint32_t* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API increments the reference count for the reference\npassed in and returns the resulting reference count.

", "type": "module", "displayName": "napi_reference_ref" }, { "textRaw": "napi_reference_unref", "name": "napi_reference_unref", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_reference_unref(napi_env env,\n                                             napi_ref ref,\n                                             uint32_t* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API decrements the reference count for the reference\npassed in and returns the resulting reference count.

", "type": "module", "displayName": "napi_reference_unref" }, { "textRaw": "napi_get_reference_value", "name": "napi_get_reference_value", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_get_reference_value(napi_env env,\n                                                 napi_ref ref,\n                                                 napi_value* result);\n
\n

the napi_value passed in or out of these methods is a handle to the\nobject to which the reference is related.

\n\n

Returns napi_ok if the API succeeded.

\n

If still valid, this API returns the napi_value representing the\nJavaScript Object associated with the napi_ref. Otherwise, result\nwill be NULL.

", "type": "module", "displayName": "napi_get_reference_value" } ], "type": "module", "displayName": "References to objects with a lifespan longer than that of the native method" }, { "textRaw": "Cleanup on exit of the current Node.js instance", "name": "cleanup_on_exit_of_the_current_node.js_instance", "desc": "

While a Node.js process typically releases all its resources when exiting,\nembedders of Node.js, or future Worker support, may require addons to register\nclean-up hooks that will be run once the current Node.js instance exits.

\n

N-API provides functions for registering and un-registering such callbacks.\nWhen those callbacks are run, all resources that are being held by the addon\nshould be freed up.

", "modules": [ { "textRaw": "napi_add_env_cleanup_hook", "name": "napi_add_env_cleanup_hook", "meta": { "added": [ "v10.2.0" ], "napiVersion": [ 3 ], "changes": [] }, "desc": "
NODE_EXTERN napi_status napi_add_env_cleanup_hook(napi_env env,\n                                                  void (*fun)(void* arg),\n                                                  void* arg);\n
\n

Registers fun as a function to be run with the arg parameter once the\ncurrent Node.js environment exits.

\n

A function can safely be specified multiple times with different\narg values. In that case, it will be called multiple times as well.\nProviding the same fun and arg values multiple times is not allowed\nand will lead the process to abort.

\n

The hooks will be called in reverse order, i.e. the most recently added one\nwill be called first.

\n

Removing this hook can be done by using napi_remove_env_cleanup_hook.\nTypically, that happens when the resource for which this hook was added\nis being torn down anyway.

", "type": "module", "displayName": "napi_add_env_cleanup_hook" }, { "textRaw": "napi_remove_env_cleanup_hook", "name": "napi_remove_env_cleanup_hook", "meta": { "added": [ "v10.2.0" ], "napiVersion": [ 3 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_remove_env_cleanup_hook(napi_env env,\n                                                     void (*fun)(void* arg),\n                                                     void* arg);\n
\n

Unregisters fun as a function to be run with the arg parameter once the\ncurrent Node.js environment exits. Both the argument and the function value\nneed to be exact matches.

\n

The function must have originally been registered\nwith napi_add_env_cleanup_hook, otherwise the process will abort.

", "type": "module", "displayName": "napi_remove_env_cleanup_hook" } ], "type": "module", "displayName": "Cleanup on exit of the current Node.js instance" } ], "type": "misc", "displayName": "Object lifetime management" }, { "textRaw": "Module registration", "name": "module_registration", "desc": "

N-API modules are registered in a manner similar to other modules\nexcept that instead of using the NODE_MODULE macro the following\nis used:

\n
NAPI_MODULE(NODE_GYP_MODULE_NAME, Init)\n
\n

The next difference is the signature for the Init method. For a N-API\nmodule it is as follows:

\n
napi_value Init(napi_env env, napi_value exports);\n
\n

The return value from Init is treated as the exports object for the module.\nThe Init method is passed an empty object via the exports parameter as a\nconvenience. If Init returns NULL, the parameter passed as exports is\nexported by the module. N-API modules cannot modify the module object but can\nspecify anything as the exports property of the module.

\n

To add the method hello as a function so that it can be called as a method\nprovided by the addon:

\n
napi_value Init(napi_env env, napi_value exports) {\n  napi_status status;\n  napi_property_descriptor desc =\n    {\"hello\", NULL, Method, NULL, NULL, NULL, napi_default, NULL};\n  status = napi_define_properties(env, exports, 1, &desc);\n  if (status != napi_ok) return NULL;\n  return exports;\n}\n
\n

To set a function to be returned by the require() for the addon:

\n
napi_value Init(napi_env env, napi_value exports) {\n  napi_value method;\n  napi_status status;\n  status = napi_create_function(env, \"exports\", NAPI_AUTO_LENGTH, Method, NULL, &method);\n  if (status != napi_ok) return NULL;\n  return method;\n}\n
\n

To define a class so that new instances can be created (often used with\nObject wrap):

\n
// NOTE: partial example, not all referenced code is included\nnapi_value Init(napi_env env, napi_value exports) {\n  napi_status status;\n  napi_property_descriptor properties[] = {\n    { \"value\", NULL, NULL, GetValue, SetValue, NULL, napi_default, NULL },\n    DECLARE_NAPI_METHOD(\"plusOne\", PlusOne),\n    DECLARE_NAPI_METHOD(\"multiply\", Multiply),\n  };\n\n  napi_value cons;\n  status =\n      napi_define_class(env, \"MyObject\", New, NULL, 3, properties, &cons);\n  if (status != napi_ok) return NULL;\n\n  status = napi_create_reference(env, cons, 1, &constructor);\n  if (status != napi_ok) return NULL;\n\n  status = napi_set_named_property(env, exports, \"MyObject\", cons);\n  if (status != napi_ok) return NULL;\n\n  return exports;\n}\n
\n

If the module will be loaded multiple times during the lifetime of the Node.js\nprocess, use the NAPI_MODULE_INIT macro to initialize the module:

\n
NAPI_MODULE_INIT() {\n  napi_value answer;\n  napi_status result;\n\n  status = napi_create_int64(env, 42, &answer);\n  if (status != napi_ok) return NULL;\n\n  status = napi_set_named_property(env, exports, \"answer\", answer);\n  if (status != napi_ok) return NULL;\n\n  return exports;\n}\n
\n

This macro includes NAPI_MODULE, and declares an Init function with a\nspecial name and with visibility beyond the addon. This will allow Node.js to\ninitialize the module even if it is loaded multiple times.

\n

There are a few design considerations when declaring a module that may be loaded\nmultiple times. The documentation of context-aware addons provides more\ndetails.

\n

The variables env and exports will be available inside the function body\nfollowing the macro invocation.

\n

For more details on setting properties on objects, see the section on\nWorking with JavaScript properties.

\n

For more details on building addon modules in general, refer to the existing\nAPI.

", "type": "misc", "displayName": "Module registration" }, { "textRaw": "Working with JavaScript values", "name": "working_with_javascript_values", "desc": "

N-API exposes a set of APIs to create all types of JavaScript values.\nSome of these types are documented under Section 6\nof the ECMAScript Language Specification.

\n

Fundamentally, these APIs are used to do one of the following:

\n
    \n
  1. Create a new JavaScript object
    2. \n
  2. Convert from a primitive C type to an N-API value
    3. \n
  3. Convert from N-API value to a primitive C type
    4. \n
  4. Get global instances including undefined and null
    5. \n
\n

N-API values are represented by the type napi_value.\nAny N-API call that requires a JavaScript value takes in a napi_value.\nIn some cases, the API does check the type of the napi_value up-front.\nHowever, for better performance, it's better for the caller to make sure that\nthe napi_value in question is of the JavaScript type expected by the API.

", "modules": [ { "textRaw": "Enum types", "name": "enum_types", "modules": [ { "textRaw": "napi_key_collection_mode", "name": "napi_key_collection_mode", "meta": { "added": [ "v13.7.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
typedef enum {\n  napi_key_include_prototypes,\n  napi_key_own_only\n} napi_key_collection_mode;\n
\n

Describes the Keys/Properties filter enums:

\n

napi_key_collection_mode limits the range of collected properties.

\n

napi_key_own_only limits the collected properties to the given\nobject only. napi_key_include_prototypes will include all keys\nof the objects's prototype chain as well.

", "type": "module", "displayName": "napi_key_collection_mode" }, { "textRaw": "napi_key_filter", "name": "napi_key_filter", "meta": { "added": [ "v13.7.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
typedef enum {\n  napi_key_all_properties = 0,\n  napi_key_writable = 1,\n  napi_key_enumerable = 1 << 1,\n  napi_key_configurable = 1 << 2,\n  napi_key_skip_strings = 1 << 3,\n  napi_key_skip_symbols = 1 << 4\n} napi_key_filter;\n
\n

Property filter bits. They can be or'ed to build a composite filter.

", "type": "module", "displayName": "napi_key_filter" }, { "textRaw": "napi_key_conversion", "name": "napi_key_conversion", "meta": { "added": [ "v13.7.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
typedef enum {\n  napi_key_keep_numbers,\n  napi_key_numbers_to_strings\n} napi_key_conversion;\n
\n

napi_key_numbers_to_strings will convert integer indices to\nstrings. napi_key_keep_numbers will return numbers for integer\nindices.

", "type": "module", "displayName": "napi_key_conversion" }, { "textRaw": "napi_valuetype", "name": "napi_valuetype", "desc": "
typedef enum {\n  // ES6 types (corresponds to typeof)\n  napi_undefined,\n  napi_null,\n  napi_boolean,\n  napi_number,\n  napi_string,\n  napi_symbol,\n  napi_object,\n  napi_function,\n  napi_external,\n  napi_bigint,\n} napi_valuetype;\n
\n

Describes the type of a napi_value. This generally corresponds to the types\ndescribed in Section 6.1 of the ECMAScript Language Specification.\nIn addition to types in that section, napi_valuetype can also represent\nFunctions and Objects with external data.

\n

A JavaScript value of type napi_external appears in JavaScript as a plain\nobject such that no properties can be set on it, and no prototype.

", "type": "module", "displayName": "napi_valuetype" }, { "textRaw": "napi_typedarray_type", "name": "napi_typedarray_type", "desc": "
typedef enum {\n  napi_int8_array,\n  napi_uint8_array,\n  napi_uint8_clamped_array,\n  napi_int16_array,\n  napi_uint16_array,\n  napi_int32_array,\n  napi_uint32_array,\n  napi_float32_array,\n  napi_float64_array,\n  napi_bigint64_array,\n  napi_biguint64_array,\n} napi_typedarray_type;\n
\n

This represents the underlying binary scalar datatype of the TypedArray.\nElements of this enum correspond to\nSection 22.2 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_typedarray_type" } ], "type": "module", "displayName": "Enum types" }, { "textRaw": "Object creation functions", "name": "object_creation_functions", "modules": [ { "textRaw": "napi_create_array", "name": "napi_create_array", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_array(napi_env env, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns an N-API value corresponding to a JavaScript Array type.\nJavaScript arrays are described in\nSection 22.1 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_array" }, { "textRaw": "napi_create_array_with_length", "name": "napi_create_array_with_length", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_array_with_length(napi_env env,\n                                          size_t length,\n                                          napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns an N-API value corresponding to a JavaScript Array type.\nThe Array's length property is set to the passed-in length parameter.\nHowever, the underlying buffer is not guaranteed to be pre-allocated by the VM\nwhen the array is created. That behavior is left to the underlying VM\nimplementation. If the buffer must be a contiguous block of memory that can be\ndirectly read and/or written via C, consider using\nnapi_create_external_arraybuffer.

\n

JavaScript arrays are described in\nSection 22.1 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_array_with_length" }, { "textRaw": "napi_create_arraybuffer", "name": "napi_create_arraybuffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_arraybuffer(napi_env env,\n                                    size_t byte_length,\n                                    void** data,\n                                    napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns an N-API value corresponding to a JavaScript ArrayBuffer.\nArrayBuffers are used to represent fixed-length binary data buffers. They are\nnormally used as a backing-buffer for TypedArray objects.\nThe ArrayBuffer allocated will have an underlying byte buffer whose size is\ndetermined by the length parameter that's passed in.\nThe underlying buffer is optionally returned back to the caller in case the\ncaller wants to directly manipulate the buffer. This buffer can only be\nwritten to directly from native code. To write to this buffer from JavaScript,\na typed array or DataView object would need to be created.

\n

JavaScript ArrayBuffer objects are described in\nSection 24.1 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_arraybuffer" }, { "textRaw": "napi_create_buffer", "name": "napi_create_buffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_buffer(napi_env env,\n                               size_t size,\n                               void** data,\n                               napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a node::Buffer object. While this is still a\nfully-supported data structure, in most cases using a TypedArray will suffice.

", "type": "module", "displayName": "napi_create_buffer" }, { "textRaw": "napi_create_buffer_copy", "name": "napi_create_buffer_copy", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_buffer_copy(napi_env env,\n                                    size_t length,\n                                    const void* data,\n                                    void** result_data,\n                                    napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a node::Buffer object and initializes it with data copied\nfrom the passed-in buffer. While this is still a fully-supported data\nstructure, in most cases using a TypedArray will suffice.

", "type": "module", "displayName": "napi_create_buffer_copy" }, { "textRaw": "napi_create_date", "name": "napi_create_date", "meta": { "added": [ "v11.11.0", "v10.17.0" ], "napiVersion": [ 5 ], "changes": [] }, "desc": "
napi_status napi_create_date(napi_env env,\n                             double time,\n                             napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API does not observe leap seconds; they are ignored, as\nECMAScript aligns with POSIX time specification.

\n

This API allocates a JavaScript Date object.

\n

JavaScript Date objects are described in\nSection 20.3 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_date" }, { "textRaw": "napi_create_external", "name": "napi_create_external", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_external(napi_env env,\n                                 void* data,\n                                 napi_finalize finalize_cb,\n                                 void* finalize_hint,\n                                 napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a JavaScript value with external data attached to it. This\nis used to pass external data through JavaScript code, so it can be retrieved\nlater by native code using napi_get_value_external.

\n

The API adds a napi_finalize callback which will be called when the JavaScript\nobject just created is ready for garbage collection. It is similar to\nnapi_wrap() except that:

\n\n

The created value is not an object, and therefore does not support additional\nproperties. It is considered a distinct value type: calling napi_typeof() with\nan external value yields napi_external.

", "type": "module", "displayName": "napi_create_external" }, { "textRaw": "napi_create_external_arraybuffer", "name": "napi_create_external_arraybuffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status\nnapi_create_external_arraybuffer(napi_env env,\n                                 void* external_data,\n                                 size_t byte_length,\n                                 napi_finalize finalize_cb,\n                                 void* finalize_hint,\n                                 napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns an N-API value corresponding to a JavaScript ArrayBuffer.\nThe underlying byte buffer of the ArrayBuffer is externally allocated and\nmanaged. The caller must ensure that the byte buffer remains valid until the\nfinalize callback is called.

\n

The API adds a napi_finalize callback which will be called when the JavaScript\nobject just created is ready for garbage collection. It is similar to\nnapi_wrap() except that:

\n\n

JavaScript ArrayBuffers are described in\nSection 24.1 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_external_arraybuffer" }, { "textRaw": "napi_create_external_buffer", "name": "napi_create_external_buffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_external_buffer(napi_env env,\n                                        size_t length,\n                                        void* data,\n                                        napi_finalize finalize_cb,\n                                        void* finalize_hint,\n                                        napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a node::Buffer object and initializes it with data\nbacked by the passed in buffer. While this is still a fully-supported data\nstructure, in most cases using a TypedArray will suffice.

\n

The API adds a napi_finalize callback which will be called when the JavaScript\nobject just created is ready for garbage collection. It is similar to\nnapi_wrap() except that:

\n\n

For Node.js >=4 Buffers are Uint8Arrays.

", "type": "module", "displayName": "napi_create_external_buffer" }, { "textRaw": "napi_create_object", "name": "napi_create_object", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_object(napi_env env, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a default JavaScript Object.\nIt is the equivalent of doing new Object() in JavaScript.

\n

The JavaScript Object type is described in Section 6.1.7 of the\nECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_object" }, { "textRaw": "napi_create_symbol", "name": "napi_create_symbol", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_symbol(napi_env env,\n                               napi_value description,\n                               napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript Symbol object from a UTF8-encoded C string.

\n

The JavaScript Symbol type is described in Section 19.4\nof the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_symbol" }, { "textRaw": "napi_create_typedarray", "name": "napi_create_typedarray", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_typedarray(napi_env env,\n                                   napi_typedarray_type type,\n                                   size_t length,\n                                   napi_value arraybuffer,\n                                   size_t byte_offset,\n                                   napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript TypedArray object over an existing\nArrayBuffer. TypedArray objects provide an array-like view over an\nunderlying data buffer where each element has the same underlying binary scalar\ndatatype.

\n

It's required that (length * size_of_element) + byte_offset should\nbe <= the size in bytes of the array passed in. If not, a RangeError exception\nis raised.

\n

JavaScript TypedArray objects are described in\nSection 22.2 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_typedarray" }, { "textRaw": "napi_create_dataview", "name": "napi_create_dataview", "meta": { "added": [ "v8.3.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_dataview(napi_env env,\n                                 size_t byte_length,\n                                 napi_value arraybuffer,\n                                 size_t byte_offset,\n                                 napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript DataView object over an existing ArrayBuffer.\nDataView objects provide an array-like view over an underlying data buffer,\nbut one which allows items of different size and type in the ArrayBuffer.

\n

It is required that byte_length + byte_offset is less than or equal to the\nsize in bytes of the array passed in. If not, a RangeError exception is\nraised.

\n

JavaScript DataView objects are described in\nSection 24.3 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_dataview" } ], "type": "module", "displayName": "Object creation functions" }, { "textRaw": "Functions to convert from C types to N-API", "name": "functions_to_convert_from_c_types_to_n-api", "modules": [ { "textRaw": "napi_create_int32", "name": "napi_create_int32", "meta": { "added": [ "v8.4.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_int32(napi_env env, int32_t value, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to convert from the C int32_t type to the JavaScript\nNumber type.

\n

The JavaScript Number type is described in\nSection 6.1.6 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_int32" }, { "textRaw": "napi_create_uint32", "name": "napi_create_uint32", "meta": { "added": [ "v8.4.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_uint32(napi_env env, uint32_t value, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to convert from the C uint32_t type to the JavaScript\nNumber type.

\n

The JavaScript Number type is described in\nSection 6.1.6 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_uint32" }, { "textRaw": "napi_create_int64", "name": "napi_create_int64", "meta": { "added": [ "v8.4.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_int64(napi_env env, int64_t value, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to convert from the C int64_t type to the JavaScript\nNumber type.

\n

The JavaScript Number type is described in Section 6.1.6\nof the ECMAScript Language Specification. Note the complete range of int64_t\ncannot be represented with full precision in JavaScript. Integer values\noutside the range of Number.MIN_SAFE_INTEGER -(2^53 - 1) -\nNumber.MAX_SAFE_INTEGER (2^53 - 1) will lose precision.

", "type": "module", "displayName": "napi_create_int64" }, { "textRaw": "napi_create_double", "name": "napi_create_double", "meta": { "added": [ "v8.4.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_double(napi_env env, double value, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to convert from the C double type to the JavaScript\nNumber type.

\n

The JavaScript Number type is described in\nSection 6.1.6 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_double" }, { "textRaw": "napi_create_bigint_int64", "name": "napi_create_bigint_int64", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_create_bigint_int64(napi_env env,\n                                     int64_t value,\n                                     napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API converts the C int64_t type to the JavaScript BigInt type.

", "type": "module", "displayName": "napi_create_bigint_int64" }, { "textRaw": "napi_create_bigint_uint64", "name": "napi_create_bigint_uint64", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_create_bigint_uint64(napi_env env,\n                                      uint64_t value,\n                                      napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API converts the C uint64_t type to the JavaScript BigInt type.

", "type": "module", "displayName": "napi_create_bigint_uint64" }, { "textRaw": "napi_create_bigint_words", "name": "napi_create_bigint_words", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_create_bigint_words(napi_env env,\n                                     int sign_bit,\n                                     size_t word_count,\n                                     const uint64_t* words,\n                                     napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API converts an array of unsigned 64-bit words into a single BigInt\nvalue.

\n

The resulting BigInt is calculated as: (–1)sign_bit (words[0]\n× (264)0 + words[1] × (264)1 + …)

", "type": "module", "displayName": "napi_create_bigint_words" }, { "textRaw": "napi_create_string_latin1", "name": "napi_create_string_latin1", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_string_latin1(napi_env env,\n                                      const char* str,\n                                      size_t length,\n                                      napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript String object from an ISO-8859-1-encoded C\nstring. The native string is copied.

\n

The JavaScript String type is described in\nSection 6.1.4 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_string_latin1" }, { "textRaw": "napi_create_string_utf16", "name": "napi_create_string_utf16", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_string_utf16(napi_env env,\n                                     const char16_t* str,\n                                     size_t length,\n                                     napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript String object from a UTF16-LE-encoded C string.\nThe native string is copied.

\n

The JavaScript String type is described in\nSection 6.1.4 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_string_utf16" }, { "textRaw": "napi_create_string_utf8", "name": "napi_create_string_utf8", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_string_utf8(napi_env env,\n                                    const char* str,\n                                    size_t length,\n                                    napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a JavaScript String object from a UTF8-encoded C string.\nThe native string is copied.

\n

The JavaScript String type is described in\nSection 6.1.4 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_create_string_utf8" } ], "type": "module", "displayName": "Functions to convert from C types to N-API" }, { "textRaw": "Functions to convert from N-API to C types", "name": "functions_to_convert_from_n-api_to_c_types", "modules": [ { "textRaw": "napi_get_array_length", "name": "napi_get_array_length", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_array_length(napi_env env,\n                                  napi_value value,\n                                  uint32_t* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the length of an array.

\n

Array length is described in Section 22.1.4.1 of the ECMAScript Language\nSpecification.

", "type": "module", "displayName": "napi_get_array_length" }, { "textRaw": "napi_get_arraybuffer_info", "name": "napi_get_arraybuffer_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_arraybuffer_info(napi_env env,\n                                      napi_value arraybuffer,\n                                      void** data,\n                                      size_t* byte_length)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to retrieve the underlying data buffer of an ArrayBuffer and\nits length.

\n

WARNING: Use caution while using this API. The lifetime of the underlying data\nbuffer is managed by the ArrayBuffer even after it's returned. A\npossible safe way to use this API is in conjunction with\nnapi_create_reference, which can be used to guarantee control over the\nlifetime of the ArrayBuffer. It's also safe to use the returned data buffer\nwithin the same callback as long as there are no calls to other APIs that might\ntrigger a GC.

", "type": "module", "displayName": "napi_get_arraybuffer_info" }, { "textRaw": "napi_get_buffer_info", "name": "napi_get_buffer_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_buffer_info(napi_env env,\n                                 napi_value value,\n                                 void** data,\n                                 size_t* length)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to retrieve the underlying data buffer of a node::Buffer\nand it's length.

\n

Warning: Use caution while using this API since the underlying data buffer's\nlifetime is not guaranteed if it's managed by the VM.

", "type": "module", "displayName": "napi_get_buffer_info" }, { "textRaw": "napi_get_prototype", "name": "napi_get_prototype", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_prototype(napi_env env,\n                               napi_value object,\n                               napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

", "type": "module", "displayName": "napi_get_prototype" }, { "textRaw": "napi_get_typedarray_info", "name": "napi_get_typedarray_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_typedarray_info(napi_env env,\n                                     napi_value typedarray,\n                                     napi_typedarray_type* type,\n                                     size_t* length,\n                                     void** data,\n                                     napi_value* arraybuffer,\n                                     size_t* byte_offset)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns various properties of a typed array.

\n

Warning: Use caution while using this API since the underlying data buffer\nis managed by the VM.

", "type": "module", "displayName": "napi_get_typedarray_info" }, { "textRaw": "napi_get_dataview_info", "name": "napi_get_dataview_info", "meta": { "added": [ "v8.3.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_dataview_info(napi_env env,\n                                   napi_value dataview,\n                                   size_t* byte_length,\n                                   void** data,\n                                   napi_value* arraybuffer,\n                                   size_t* byte_offset)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns various properties of a DataView.

", "type": "module", "displayName": "napi_get_dataview_info" }, { "textRaw": "napi_get_date_value", "name": "napi_get_date_value", "meta": { "added": [ "v11.11.0", "v10.17.0" ], "napiVersion": [ 5 ], "changes": [] }, "desc": "
napi_status napi_get_date_value(napi_env env,\n                                napi_value value,\n                                double* result)\n
\n\n

This API does not observe leap seconds; they are ignored, as\nECMAScript aligns with POSIX time specification.

\n

Returns napi_ok if the API succeeded. If a non-date napi_value is passed\nin it returns napi_date_expected.

\n

This API returns the C double primitive of time value for the given JavaScript\nDate.

", "type": "module", "displayName": "napi_get_date_value" }, { "textRaw": "napi_get_value_bool", "name": "napi_get_value_bool", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_bool(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-boolean napi_value is\npassed in it returns napi_boolean_expected.

\n

This API returns the C boolean primitive equivalent of the given JavaScript\nBoolean.

", "type": "module", "displayName": "napi_get_value_bool" }, { "textRaw": "napi_get_value_double", "name": "napi_get_value_double", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_double(napi_env env,\n                                  napi_value value,\n                                  double* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-number napi_value is passed\nin it returns napi_number_expected.

\n

This API returns the C double primitive equivalent of the given JavaScript\nNumber.

", "type": "module", "displayName": "napi_get_value_double" }, { "textRaw": "napi_get_value_bigint_int64", "name": "napi_get_value_bigint_int64", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_get_value_bigint_int64(napi_env env,\n                                        napi_value value,\n                                        int64_t* result,\n                                        bool* lossless);\n
\n\n

Returns napi_ok if the API succeeded. If a non-BigInt is passed in it\nreturns napi_bigint_expected.

\n

This API returns the C int64_t primitive equivalent of the given JavaScript\nBigInt. If needed it will truncate the value, setting lossless to false.

", "type": "module", "displayName": "napi_get_value_bigint_int64" }, { "textRaw": "napi_get_value_bigint_uint64", "name": "napi_get_value_bigint_uint64", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_get_value_bigint_uint64(napi_env env,\n                                        napi_value value,\n                                        uint64_t* result,\n                                        bool* lossless);\n
\n\n

Returns napi_ok if the API succeeded. If a non-BigInt is passed in it\nreturns napi_bigint_expected.

\n

This API returns the C uint64_t primitive equivalent of the given JavaScript\nBigInt. If needed it will truncate the value, setting lossless to false.

", "type": "module", "displayName": "napi_get_value_bigint_uint64" }, { "textRaw": "napi_get_value_bigint_words", "name": "napi_get_value_bigint_words", "meta": { "added": [ "v10.7.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_status napi_get_value_bigint_words(napi_env env,\n                                        napi_value value,\n                                        int* sign_bit,\n                                        size_t* word_count,\n                                        uint64_t* words);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API converts a single BigInt value into a sign bit, 64-bit little-endian\narray, and the number of elements in the array. sign_bit and words may be\nboth set to NULL, in order to get only word_count.

", "type": "module", "displayName": "napi_get_value_bigint_words" }, { "textRaw": "napi_get_value_external", "name": "napi_get_value_external", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_external(napi_env env,\n                                    napi_value value,\n                                    void** result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-external napi_value is\npassed in it returns napi_invalid_arg.

\n

This API retrieves the external data pointer that was previously passed to\nnapi_create_external().

", "type": "module", "displayName": "napi_get_value_external" }, { "textRaw": "napi_get_value_int32", "name": "napi_get_value_int32", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_int32(napi_env env,\n                                 napi_value value,\n                                 int32_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-number napi_value\nis passed in napi_number_expected.

\n

This API returns the C int32 primitive equivalent\nof the given JavaScript Number.

\n

If the number exceeds the range of the 32 bit integer, then the result is\ntruncated to the equivalent of the bottom 32 bits. This can result in a large\npositive number becoming a negative number if the value is > 2^31 -1.

\n

Non-finite number values (NaN, +Infinity, or -Infinity) set the\nresult to zero.

", "type": "module", "displayName": "napi_get_value_int32" }, { "textRaw": "napi_get_value_int64", "name": "napi_get_value_int64", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_int64(napi_env env,\n                                 napi_value value,\n                                 int64_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-number napi_value\nis passed in it returns napi_number_expected.

\n

This API returns the C int64 primitive equivalent of the given JavaScript\nNumber.

\n

Number values outside the range of Number.MIN_SAFE_INTEGER\n-(2^53 - 1) - Number.MAX_SAFE_INTEGER (2^53 - 1) will lose precision.

\n

Non-finite number values (NaN, +Infinity, or -Infinity) set the\nresult to zero.

", "type": "module", "displayName": "napi_get_value_int64" }, { "textRaw": "napi_get_value_string_latin1", "name": "napi_get_value_string_latin1", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_string_latin1(napi_env env,\n                                         napi_value value,\n                                         char* buf,\n                                         size_t bufsize,\n                                         size_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-String napi_value\nis passed in it returns napi_string_expected.

\n

This API returns the ISO-8859-1-encoded string corresponding the value passed\nin.

", "type": "module", "displayName": "napi_get_value_string_latin1" }, { "textRaw": "napi_get_value_string_utf8", "name": "napi_get_value_string_utf8", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_string_utf8(napi_env env,\n                                       napi_value value,\n                                       char* buf,\n                                       size_t bufsize,\n                                       size_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-String napi_value\nis passed in it returns napi_string_expected.

\n

This API returns the UTF8-encoded string corresponding the value passed in.

", "type": "module", "displayName": "napi_get_value_string_utf8" }, { "textRaw": "napi_get_value_string_utf16", "name": "napi_get_value_string_utf16", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_string_utf16(napi_env env,\n                                        napi_value value,\n                                        char16_t* buf,\n                                        size_t bufsize,\n                                        size_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-String napi_value\nis passed in it returns napi_string_expected.

\n

This API returns the UTF16-encoded string corresponding the value passed in.

", "type": "module", "displayName": "napi_get_value_string_utf16" }, { "textRaw": "napi_get_value_uint32", "name": "napi_get_value_uint32", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_value_uint32(napi_env env,\n                                  napi_value value,\n                                  uint32_t* result)\n
\n\n

Returns napi_ok if the API succeeded. If a non-number napi_value\nis passed in it returns napi_number_expected.

\n

This API returns the C primitive equivalent of the given napi_value as a\nuint32_t.

", "type": "module", "displayName": "napi_get_value_uint32" } ], "type": "module", "displayName": "Functions to convert from N-API to C types" }, { "textRaw": "Functions to get global instances", "name": "functions_to_get_global_instances", "modules": [ { "textRaw": "napi_get_boolean", "name": "napi_get_boolean", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_boolean(napi_env env, bool value, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API is used to return the JavaScript singleton object that is used to\nrepresent the given boolean value.

", "type": "module", "displayName": "napi_get_boolean" }, { "textRaw": "napi_get_global", "name": "napi_get_global", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_global(napi_env env, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the global object.

", "type": "module", "displayName": "napi_get_global" }, { "textRaw": "napi_get_null", "name": "napi_get_null", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_null(napi_env env, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the null object.

", "type": "module", "displayName": "napi_get_null" }, { "textRaw": "napi_get_undefined", "name": "napi_get_undefined", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_undefined(napi_env env, napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the Undefined object.

", "type": "module", "displayName": "napi_get_undefined" } ], "type": "module", "displayName": "Functions to get global instances" } ], "type": "misc", "displayName": "Working with JavaScript values" }, { "textRaw": "Working with JavaScript values and abstract operations", "name": "working_with_javascript_values_and_abstract_operations", "desc": "

N-API exposes a set of APIs to perform some abstract operations on JavaScript\nvalues. Some of these operations are documented under Section 7\nof the ECMAScript Language Specification.

\n

These APIs support doing one of the following:

\n
    \n
  1. Coerce JavaScript values to specific JavaScript types (such as Number or\nString).
    2. \n
  2. Check the type of a JavaScript value.
    3. \n
  3. Check for equality between two JavaScript values.
    4. \n
", "modules": [ { "textRaw": "napi_coerce_to_bool", "name": "napi_coerce_to_bool", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_coerce_to_bool(napi_env env,\n                                napi_value value,\n                                napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API implements the abstract operation ToBoolean() as defined in\nSection 7.1.2 of the ECMAScript Language Specification.\nThis API can be re-entrant if getters are defined on the passed-in Object.

", "type": "module", "displayName": "napi_coerce_to_bool" }, { "textRaw": "napi_coerce_to_number", "name": "napi_coerce_to_number", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_coerce_to_number(napi_env env,\n                                  napi_value value,\n                                  napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API implements the abstract operation ToNumber() as defined in\nSection 7.1.3 of the ECMAScript Language Specification.\nThis API can be re-entrant if getters are defined on the passed-in Object.

", "type": "module", "displayName": "napi_coerce_to_number" }, { "textRaw": "napi_coerce_to_object", "name": "napi_coerce_to_object", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_coerce_to_object(napi_env env,\n                                  napi_value value,\n                                  napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API implements the abstract operation ToObject() as defined in\nSection 7.1.13 of the ECMAScript Language Specification.\nThis API can be re-entrant if getters are defined on the passed-in Object.

", "type": "module", "displayName": "napi_coerce_to_object" }, { "textRaw": "napi_coerce_to_string", "name": "napi_coerce_to_string", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_coerce_to_string(napi_env env,\n                                  napi_value value,\n                                  napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API implements the abstract operation ToString() as defined in\nSection 7.1.13 of the ECMAScript Language Specification.\nThis API can be re-entrant if getters are defined on the passed-in Object.

", "type": "module", "displayName": "napi_coerce_to_string" }, { "textRaw": "napi_typeof", "name": "napi_typeof", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_typeof(napi_env env, napi_value value, napi_valuetype* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n\n

This API represents behavior similar to invoking the typeof Operator on\nthe object as defined in Section 12.5.5 of the ECMAScript Language\nSpecification. However, it has support for detecting an External value.\nIf value has a type that is invalid, an error is returned.

", "type": "module", "displayName": "napi_typeof" }, { "textRaw": "napi_instanceof", "name": "napi_instanceof", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_instanceof(napi_env env,\n                            napi_value object,\n                            napi_value constructor,\n                            bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API represents invoking the instanceof Operator on the object as\ndefined in Section 12.10.4 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_instanceof" }, { "textRaw": "napi_is_array", "name": "napi_is_array", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_array(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API represents invoking the IsArray operation on the object\nas defined in Section 7.2.2 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_is_array" }, { "textRaw": "napi_is_arraybuffer", "name": "napi_is_arraybuffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_arraybuffer(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is an array buffer.

", "type": "module", "displayName": "napi_is_arraybuffer" }, { "textRaw": "napi_is_buffer", "name": "napi_is_buffer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_buffer(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is a buffer.

", "type": "module", "displayName": "napi_is_buffer" }, { "textRaw": "napi_is_date", "name": "napi_is_date", "meta": { "added": [ "v11.11.0", "v10.17.0" ], "napiVersion": [ 5 ], "changes": [] }, "desc": "
napi_status napi_is_date(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is a date.

", "type": "module", "displayName": "napi_is_date" }, { "textRaw": "napi_is_error", "name": "napi_is_error", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_error(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is an Error.

", "type": "module", "displayName": "napi_is_error" }, { "textRaw": "napi_is_typedarray", "name": "napi_is_typedarray", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_typedarray(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is a typed array.

", "type": "module", "displayName": "napi_is_typedarray" }, { "textRaw": "napi_is_dataview", "name": "napi_is_dataview", "meta": { "added": [ "v8.3.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_dataview(napi_env env, napi_value value, bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in is a DataView.

", "type": "module", "displayName": "napi_is_dataview" }, { "textRaw": "napi_strict_equals", "name": "napi_strict_equals", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_strict_equals(napi_env env,\n                               napi_value lhs,\n                               napi_value rhs,\n                               bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API represents the invocation of the Strict Equality algorithm as\ndefined in Section 7.2.14 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_strict_equals" }, { "textRaw": "napi_detach_arraybuffer", "name": "napi_detach_arraybuffer", "meta": { "added": [ "v13.0.0", "v12.16.0" ], "changes": [] }, "stability": 1, "stabilityText": "Experimental", "desc": "
napi_status napi_detach_arraybuffer(napi_env env,\n                                    napi_value arraybuffer)\n
\n\n

Returns napi_ok if the API succeeded. If a non-detachable ArrayBuffer is\npassed in it returns napi_detachable_arraybuffer_expected.

\n

Generally, an ArrayBuffer is non-detachable if it has been detached before.\nThe engine may impose additional conditions on whether an ArrayBuffer is\ndetachable. For example, V8 requires that the ArrayBuffer be external,\nthat is, created with napi_create_external_arraybuffer.

\n

This API represents the invocation of the ArrayBuffer detach operation as\ndefined in Section 24.1.1.3 of the ECMAScript Language Specification.

", "type": "module", "displayName": "napi_detach_arraybuffer" }, { "textRaw": "napi_is_detached_arraybuffer", "name": "napi_is_detached_arraybuffer", "meta": { "added": [ "v13.3.0", "v12.16.0" ], "changes": [] }, "stability": 1, "stabilityText": "Experimental", "desc": "
napi_status napi_is_detached_arraybuffer(napi_env env,\n                                         napi_value arraybuffer,\n                                         bool* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

The ArrayBuffer is considered detached if its internal data is null.

\n

This API represents the invocation of the ArrayBuffer IsDetachedBuffer\noperation as defined in Section 24.1.1.2 of the ECMAScript Language\nSpecification.

", "type": "module", "displayName": "napi_is_detached_arraybuffer" } ], "type": "misc", "displayName": "Working with JavaScript values and abstract operations" }, { "textRaw": "Working with JavaScript properties", "name": "working_with_javascript_properties", "desc": "

N-API exposes a set of APIs to get and set properties on JavaScript\nobjects. Some of these types are documented under Section 7 of the\nECMAScript Language Specification.

\n

Properties in JavaScript are represented as a tuple of a key and a value.\nFundamentally, all property keys in N-API can be represented in one of the\nfollowing forms:

\n\n

N-API values are represented by the type napi_value.\nAny N-API call that requires a JavaScript value takes in a napi_value.\nHowever, it's the caller's responsibility to make sure that the\nnapi_value in question is of the JavaScript type expected by the API.

\n

The APIs documented in this section provide a simple interface to\nget and set properties on arbitrary JavaScript objects represented by\nnapi_value.

\n

For instance, consider the following JavaScript code snippet:

\n
const obj = {};\nobj.myProp = 123;\n
\n

The equivalent can be done using N-API values with the following snippet:

\n
napi_status status = napi_generic_failure;\n\n// const obj = {}\nnapi_value obj, value;\nstatus = napi_create_object(env, &obj);\nif (status != napi_ok) return status;\n\n// Create a napi_value for 123\nstatus = napi_create_int32(env, 123, &value);\nif (status != napi_ok) return status;\n\n// obj.myProp = 123\nstatus = napi_set_named_property(env, obj, \"myProp\", value);\nif (status != napi_ok) return status;\n
\n

Indexed properties can be set in a similar manner. Consider the following\nJavaScript snippet:

\n
const arr = [];\narr[123] = 'hello';\n
\n

The equivalent can be done using N-API values with the following snippet:

\n
napi_status status = napi_generic_failure;\n\n// const arr = [];\nnapi_value arr, value;\nstatus = napi_create_array(env, &arr);\nif (status != napi_ok) return status;\n\n// Create a napi_value for 'hello'\nstatus = napi_create_string_utf8(env, \"hello\", NAPI_AUTO_LENGTH, &value);\nif (status != napi_ok) return status;\n\n// arr[123] = 'hello';\nstatus = napi_set_element(env, arr, 123, value);\nif (status != napi_ok) return status;\n
\n

Properties can be retrieved using the APIs described in this section.\nConsider the following JavaScript snippet:

\n
const arr = [];\nconst value = arr[123];\n
\n

The following is the approximate equivalent of the N-API counterpart:

\n
napi_status status = napi_generic_failure;\n\n// const arr = []\nnapi_value arr, value;\nstatus = napi_create_array(env, &arr);\nif (status != napi_ok) return status;\n\n// const value = arr[123]\nstatus = napi_get_element(env, arr, 123, &value);\nif (status != napi_ok) return status;\n
\n

Finally, multiple properties can also be defined on an object for performance\nreasons. Consider the following JavaScript:

\n
const obj = {};\nObject.defineProperties(obj, {\n  'foo': { value: 123, writable: true, configurable: true, enumerable: true },\n  'bar': { value: 456, writable: true, configurable: true, enumerable: true }\n});\n
\n

The following is the approximate equivalent of the N-API counterpart:

\n
napi_status status = napi_status_generic_failure;\n\n// const obj = {};\nnapi_value obj;\nstatus = napi_create_object(env, &obj);\nif (status != napi_ok) return status;\n\n// Create napi_values for 123 and 456\nnapi_value fooValue, barValue;\nstatus = napi_create_int32(env, 123, &fooValue);\nif (status != napi_ok) return status;\nstatus = napi_create_int32(env, 456, &barValue);\nif (status != napi_ok) return status;\n\n// Set the properties\nnapi_property_descriptor descriptors[] = {\n  { \"foo\", NULL, NULL, NULL, NULL, fooValue, napi_default, NULL },\n  { \"bar\", NULL, NULL, NULL, NULL, barValue, napi_default, NULL }\n}\nstatus = napi_define_properties(env,\n                                obj,\n                                sizeof(descriptors) / sizeof(descriptors[0]),\n                                descriptors);\nif (status != napi_ok) return status;\n
", "modules": [ { "textRaw": "Structures", "name": "structures", "modules": [ { "textRaw": "napi_property_attributes", "name": "napi_property_attributes", "desc": "
typedef enum {\n  napi_default = 0,\n  napi_writable = 1 << 0,\n  napi_enumerable = 1 << 1,\n  napi_configurable = 1 << 2,\n\n  // Used with napi_define_class to distinguish static properties\n  // from instance properties. Ignored by napi_define_properties.\n  napi_static = 1 << 10,\n} napi_property_attributes;\n
\n

napi_property_attributes are flags used to control the behavior of properties\nset on a JavaScript object. Other than napi_static they correspond to the\nattributes listed in Section 6.1.7.1\nof the ECMAScript Language Specification.\nThey can be one or more of the following bitflags:

\n", "type": "module", "displayName": "napi_property_attributes" }, { "textRaw": "napi_property_descriptor", "name": "napi_property_descriptor", "desc": "
typedef struct {\n  // One of utf8name or name should be NULL.\n  const char* utf8name;\n  napi_value name;\n\n  napi_callback method;\n  napi_callback getter;\n  napi_callback setter;\n  napi_value value;\n\n  napi_property_attributes attributes;\n  void* data;\n} napi_property_descriptor;\n
\n", "type": "module", "displayName": "napi_property_descriptor" } ], "type": "module", "displayName": "Structures" }, { "textRaw": "Functions", "name": "functions", "modules": [ { "textRaw": "napi_get_property_names", "name": "napi_get_property_names", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_property_names(napi_env env,\n                                    napi_value object,\n                                    napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the names of the enumerable properties of object as an array\nof strings. The properties of object whose key is a symbol will not be\nincluded.

", "type": "module", "displayName": "napi_get_property_names" }, { "textRaw": "napi_get_all_property_names", "name": "napi_get_all_property_names", "meta": { "added": [ "v13.7.0", "v10.20.0" ], "napiVersion": [ 6 ], "changes": [] }, "desc": "
napi_get_all_property_names(napi_env env,\n                            napi_value object,\n                            napi_key_collection_mode key_mode,\n                            napi_key_filter key_filter,\n                            napi_key_conversion key_conversion,\n                            napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns an array containing the names of the available properties\nof this object.

", "type": "module", "displayName": "napi_get_all_property_names" }, { "textRaw": "napi_set_property", "name": "napi_set_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_set_property(napi_env env,\n                              napi_value object,\n                              napi_value key,\n                              napi_value value);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API set a property on the Object passed in.

", "type": "module", "displayName": "napi_set_property" }, { "textRaw": "napi_get_property", "name": "napi_get_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_property(napi_env env,\n                              napi_value object,\n                              napi_value key,\n                              napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API gets the requested property from the Object passed in.

", "type": "module", "displayName": "napi_get_property" }, { "textRaw": "napi_has_property", "name": "napi_has_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_has_property(napi_env env,\n                              napi_value object,\n                              napi_value key,\n                              bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in has the named property.

", "type": "module", "displayName": "napi_has_property" }, { "textRaw": "napi_delete_property", "name": "napi_delete_property", "meta": { "added": [ "v8.2.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_delete_property(napi_env env,\n                                 napi_value object,\n                                 napi_value key,\n                                 bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API attempts to delete the key own property from object.

", "type": "module", "displayName": "napi_delete_property" }, { "textRaw": "napi_has_own_property", "name": "napi_has_own_property", "meta": { "added": [ "v8.2.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_has_own_property(napi_env env,\n                                  napi_value object,\n                                  napi_value key,\n                                  bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API checks if the Object passed in has the named own property. key must\nbe a string or a Symbol, or an error will be thrown. N-API will not perform\nany conversion between data types.

", "type": "module", "displayName": "napi_has_own_property" }, { "textRaw": "napi_set_named_property", "name": "napi_set_named_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_set_named_property(napi_env env,\n                                    napi_value object,\n                                    const char* utf8Name,\n                                    napi_value value);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method is equivalent to calling napi_set_property with a napi_value\ncreated from the string passed in as utf8Name.

", "type": "module", "displayName": "napi_set_named_property" }, { "textRaw": "napi_get_named_property", "name": "napi_get_named_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_named_property(napi_env env,\n                                    napi_value object,\n                                    const char* utf8Name,\n                                    napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method is equivalent to calling napi_get_property with a napi_value\ncreated from the string passed in as utf8Name.

", "type": "module", "displayName": "napi_get_named_property" }, { "textRaw": "napi_has_named_property", "name": "napi_has_named_property", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_has_named_property(napi_env env,\n                                    napi_value object,\n                                    const char* utf8Name,\n                                    bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method is equivalent to calling napi_has_property with a napi_value\ncreated from the string passed in as utf8Name.

", "type": "module", "displayName": "napi_has_named_property" }, { "textRaw": "napi_set_element", "name": "napi_set_element", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_set_element(napi_env env,\n                             napi_value object,\n                             uint32_t index,\n                             napi_value value);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API sets and element on the Object passed in.

", "type": "module", "displayName": "napi_set_element" }, { "textRaw": "napi_get_element", "name": "napi_get_element", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_element(napi_env env,\n                             napi_value object,\n                             uint32_t index,\n                             napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API gets the element at the requested index.

", "type": "module", "displayName": "napi_get_element" }, { "textRaw": "napi_has_element", "name": "napi_has_element", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_has_element(napi_env env,\n                             napi_value object,\n                             uint32_t index,\n                             bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns if the Object passed in has an element at the\nrequested index.

", "type": "module", "displayName": "napi_has_element" }, { "textRaw": "napi_delete_element", "name": "napi_delete_element", "meta": { "added": [ "v8.2.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_delete_element(napi_env env,\n                                napi_value object,\n                                uint32_t index,\n                                bool* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API attempts to delete the specified index from object.

", "type": "module", "displayName": "napi_delete_element" }, { "textRaw": "napi_define_properties", "name": "napi_define_properties", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_define_properties(napi_env env,\n                                   napi_value object,\n                                   size_t property_count,\n                                   const napi_property_descriptor* properties);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method allows the efficient definition of multiple properties on a given\nobject. The properties are defined using property descriptors (see\nnapi_property_descriptor). Given an array of such property descriptors,\nthis API will set the properties on the object one at a time, as defined by\nDefineOwnProperty() (described in Section 9.1.6 of the ECMA-262\nspecification).

", "type": "module", "displayName": "napi_define_properties" } ], "type": "module", "displayName": "Functions" } ], "type": "misc", "displayName": "Working with JavaScript properties" }, { "textRaw": "Working with JavaScript functions", "name": "working_with_javascript_functions", "desc": "

N-API provides a set of APIs that allow JavaScript code to\ncall back into native code. N-API APIs that support calling back\ninto native code take in a callback functions represented by\nthe napi_callback type. When the JavaScript VM calls back to\nnative code, the napi_callback function provided is invoked. The APIs\ndocumented in this section allow the callback function to do the\nfollowing:

\n\n

Additionally, N-API provides a set of functions which allow calling\nJavaScript functions from native code. One can either call a function\nlike a regular JavaScript function call, or as a constructor\nfunction.

\n

Any non-NULL data which is passed to this API via the data field of the\nnapi_property_descriptor items can be associated with object and freed\nwhenever object is garbage-collected by passing both object and the data to\nnapi_add_finalizer.

", "modules": [ { "textRaw": "napi_call_function", "name": "napi_call_function", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_call_function(napi_env env,\n                                           napi_value recv,\n                                           napi_value func,\n                                           size_t argc,\n                                           const napi_value* argv,\n                                           napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method allows a JavaScript function object to be called from a native\nadd-on. This is the primary mechanism of calling back from the add-on's\nnative code into JavaScript. For the special case of calling into JavaScript\nafter an async operation, see napi_make_callback.

\n

A sample use case might look as follows. Consider the following JavaScript\nsnippet:

\n
function AddTwo(num) {\n  return num + 2;\n}\n
\n

Then, the above function can be invoked from a native add-on using the\nfollowing code:

\n
// Get the function named \"AddTwo\" on the global object\nnapi_value global, add_two, arg;\nnapi_status status = napi_get_global(env, &global);\nif (status != napi_ok) return;\n\nstatus = napi_get_named_property(env, global, \"AddTwo\", &add_two);\nif (status != napi_ok) return;\n\n// const arg = 1337\nstatus = napi_create_int32(env, 1337, &arg);\nif (status != napi_ok) return;\n\nnapi_value* argv = &arg;\nsize_t argc = 1;\n\n// AddTwo(arg);\nnapi_value return_val;\nstatus = napi_call_function(env, global, add_two, argc, argv, &return_val);\nif (status != napi_ok) return;\n\n// Convert the result back to a native type\nint32_t result;\nstatus = napi_get_value_int32(env, return_val, &result);\nif (status != napi_ok) return;\n
", "type": "module", "displayName": "napi_call_function" }, { "textRaw": "napi_create_function", "name": "napi_create_function", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_function(napi_env env,\n                                 const char* utf8name,\n                                 size_t length,\n                                 napi_callback cb,\n                                 void* data,\n                                 napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allows an add-on author to create a function object in native code.\nThis is the primary mechanism to allow calling into the add-on's native code\nfrom JavaScript.

\n

The newly created function is not automatically visible from script after this\ncall. Instead, a property must be explicitly set on any object that is visible\nto JavaScript, in order for the function to be accessible from script.

\n

In order to expose a function as part of the\nadd-on's module exports, set the newly created function on the exports\nobject. A sample module might look as follows:

\n
napi_value SayHello(napi_env env, napi_callback_info info) {\n  printf(\"Hello\\n\");\n  return NULL;\n}\n\nnapi_value Init(napi_env env, napi_value exports) {\n  napi_status status;\n\n  napi_value fn;\n  status = napi_create_function(env, NULL, 0, SayHello, NULL, &fn);\n  if (status != napi_ok) return NULL;\n\n  status = napi_set_named_property(env, exports, \"sayHello\", fn);\n  if (status != napi_ok) return NULL;\n\n  return exports;\n}\n\nNAPI_MODULE(NODE_GYP_MODULE_NAME, Init)\n
\n

Given the above code, the add-on can be used from JavaScript as follows:

\n
const myaddon = require('./addon');\nmyaddon.sayHello();\n
\n

The string passed to require() is the name of the target in binding.gyp\nresponsible for creating the .node file.

\n

Any non-NULL data which is passed to this API via the data parameter can\nbe associated with the resulting JavaScript function (which is returned in the\nresult parameter) and freed whenever the function is garbage-collected by\npassing both the JavaScript function and the data to napi_add_finalizer.

\n

JavaScript Functions are described in Section 19.2 of the ECMAScript\nLanguage Specification.

", "type": "module", "displayName": "napi_create_function" }, { "textRaw": "napi_get_cb_info", "name": "napi_get_cb_info", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_cb_info(napi_env env,\n                             napi_callback_info cbinfo,\n                             size_t* argc,\n                             napi_value* argv,\n                             napi_value* thisArg,\n                             void** data)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method is used within a callback function to retrieve details about the\ncall like the arguments and the this pointer from a given callback info.

", "type": "module", "displayName": "napi_get_cb_info" }, { "textRaw": "napi_get_new_target", "name": "napi_get_new_target", "meta": { "added": [ "v8.6.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_new_target(napi_env env,\n                                napi_callback_info cbinfo,\n                                napi_value* result)\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the new.target of the constructor call. If the current\ncallback is not a constructor call, the result is NULL.

", "type": "module", "displayName": "napi_get_new_target" }, { "textRaw": "napi_new_instance", "name": "napi_new_instance", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_new_instance(napi_env env,\n                              napi_value cons,\n                              size_t argc,\n                              napi_value* argv,\n                              napi_value* result)\n
\n\n

This method is used to instantiate a new JavaScript value using a given\nnapi_value that represents the constructor for the object. For example,\nconsider the following snippet:

\n
function MyObject(param) {\n  this.param = param;\n}\n\nconst arg = 'hello';\nconst value = new MyObject(arg);\n
\n

The following can be approximated in N-API using the following snippet:

\n
// Get the constructor function MyObject\nnapi_value global, constructor, arg, value;\nnapi_status status = napi_get_global(env, &global);\nif (status != napi_ok) return;\n\nstatus = napi_get_named_property(env, global, \"MyObject\", &constructor);\nif (status != napi_ok) return;\n\n// const arg = \"hello\"\nstatus = napi_create_string_utf8(env, \"hello\", NAPI_AUTO_LENGTH, &arg);\nif (status != napi_ok) return;\n\nnapi_value* argv = &arg;\nsize_t argc = 1;\n\n// const value = new MyObject(arg)\nstatus = napi_new_instance(env, constructor, argc, argv, &value);\n
\n

Returns napi_ok if the API succeeded.

", "type": "module", "displayName": "napi_new_instance" } ], "type": "misc", "displayName": "Working with JavaScript functions" }, { "textRaw": "Object wrap", "name": "object_wrap", "desc": "

N-API offers a way to \"wrap\" C++ classes and instances so that the class\nconstructor and methods can be called from JavaScript.

\n
    \n
  1. The napi_define_class API defines a JavaScript class with constructor,\nstatic properties and methods, and instance properties and methods that\ncorrespond to the C++ class.
    2. \n
  2. When JavaScript code invokes the constructor, the constructor callback\nuses napi_wrap to wrap a new C++ instance in a JavaScript object,\nthen returns the wrapper object.
    3. \n
  3. When JavaScript code invokes a method or property accessor on the class,\nthe corresponding napi_callback C++ function is invoked. For an instance\ncallback, napi_unwrap obtains the C++ instance that is the target of\nthe call.
    4. \n
\n

For wrapped objects it may be difficult to distinguish between a function\ncalled on a class prototype and a function called on an instance of a class.\nA common pattern used to address this problem is to save a persistent\nreference to the class constructor for later instanceof checks.

\n
napi_value MyClass_constructor = NULL;\nstatus = napi_get_reference_value(env, MyClass::es_constructor, &MyClass_constructor);\nassert(napi_ok == status);\nbool is_instance = false;\nstatus = napi_instanceof(env, es_this, MyClass_constructor, &is_instance);\nassert(napi_ok == status);\nif (is_instance) {\n  // napi_unwrap() ...\n} else {\n  // otherwise...\n}\n
\n

The reference must be freed once it is no longer needed.

", "modules": [ { "textRaw": "napi_define_class", "name": "napi_define_class", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_define_class(napi_env env,\n                              const char* utf8name,\n                              size_t length,\n                              napi_callback constructor,\n                              void* data,\n                              size_t property_count,\n                              const napi_property_descriptor* properties,\n                              napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

Defines a JavaScript class that corresponds to a C++ class, including:

\n\n

The C++ constructor callback should be a static method on the class that calls\nthe actual class constructor, then wraps the new C++ instance in a JavaScript\nobject, and returns the wrapper object. See napi_wrap() for details.

\n

The JavaScript constructor function returned from napi_define_class is\noften saved and used later, to construct new instances of the class from native\ncode, and/or check whether provided values are instances of the class. In that\ncase, to prevent the function value from being garbage-collected, create a\npersistent reference to it using napi_create_reference and ensure the\nreference count is kept >= 1.

\n

Any non-NULL data which is passed to this API via the data parameter or via\nthe data field of the napi_property_descriptor array items can be associated\nwith the resulting JavaScript constructor (which is returned in the result\nparameter) and freed whenever the class is garbage-collected by passing both\nthe JavaScript function and the data to napi_add_finalizer.

", "type": "module", "displayName": "napi_define_class" }, { "textRaw": "napi_wrap", "name": "napi_wrap", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_wrap(napi_env env,\n                      napi_value js_object,\n                      void* native_object,\n                      napi_finalize finalize_cb,\n                      void* finalize_hint,\n                      napi_ref* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

Wraps a native instance in a JavaScript object. The native instance can be\nretrieved later using napi_unwrap().

\n

When JavaScript code invokes a constructor for a class that was defined using\nnapi_define_class(), the napi_callback for the constructor is invoked.\nAfter constructing an instance of the native class, the callback must then call\nnapi_wrap() to wrap the newly constructed instance in the already-created\nJavaScript object that is the this argument to the constructor callback.\n(That this object was created from the constructor function's prototype,\nso it already has definitions of all the instance properties and methods.)

\n

Typically when wrapping a class instance, a finalize callback should be\nprovided that simply deletes the native instance that is received as the data\nargument to the finalize callback.

\n

The optional returned reference is initially a weak reference, meaning it\nhas a reference count of 0. Typically this reference count would be incremented\ntemporarily during async operations that require the instance to remain valid.

\n

Caution: The optional returned reference (if obtained) should be deleted via\nnapi_delete_reference ONLY in response to the finalize callback\ninvocation. If it is deleted before then, then the finalize callback may never\nbe invoked. Therefore, when obtaining a reference a finalize callback is also\nrequired in order to enable correct disposal of the reference.

\n

Calling napi_wrap() a second time on an object will return an error. To\nassociate another native instance with the object, use napi_remove_wrap()\nfirst.

", "type": "module", "displayName": "napi_wrap" }, { "textRaw": "napi_unwrap", "name": "napi_unwrap", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_unwrap(napi_env env,\n                        napi_value js_object,\n                        void** result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

Retrieves a native instance that was previously wrapped in a JavaScript\nobject using napi_wrap().

\n

When JavaScript code invokes a method or property accessor on the class, the\ncorresponding napi_callback is invoked. If the callback is for an instance\nmethod or accessor, then the this argument to the callback is the wrapper\nobject; the wrapped C++ instance that is the target of the call can be obtained\nthen by calling napi_unwrap() on the wrapper object.

", "type": "module", "displayName": "napi_unwrap" }, { "textRaw": "napi_remove_wrap", "name": "napi_remove_wrap", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_remove_wrap(napi_env env,\n                             napi_value js_object,\n                             void** result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

Retrieves a native instance that was previously wrapped in the JavaScript\nobject js_object using napi_wrap() and removes the wrapping. If a finalize\ncallback was associated with the wrapping, it will no longer be called when the\nJavaScript object becomes garbage-collected.

", "type": "module", "displayName": "napi_remove_wrap" }, { "textRaw": "napi_add_finalizer", "name": "napi_add_finalizer", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 5 ], "changes": [] }, "desc": "
napi_status napi_add_finalizer(napi_env env,\n                               napi_value js_object,\n                               void* native_object,\n                               napi_finalize finalize_cb,\n                               void* finalize_hint,\n                               napi_ref* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

Adds a napi_finalize callback which will be called when the JavaScript object\nin js_object is ready for garbage collection. This API is similar to\nnapi_wrap() except that:

\n\n

Caution: The optional returned reference (if obtained) should be deleted via\nnapi_delete_reference ONLY in response to the finalize callback\ninvocation. If it is deleted before then, then the finalize callback may never\nbe invoked. Therefore, when obtaining a reference a finalize callback is also\nrequired in order to enable correct disposal of the reference.

", "type": "module", "displayName": "napi_add_finalizer" } ], "type": "misc", "displayName": "Object wrap" }, { "textRaw": "Simple asynchronous operations", "name": "simple_asynchronous_operations", "desc": "

Addon modules often need to leverage async helpers from libuv as part of their\nimplementation. This allows them to schedule work to be executed asynchronously\nso that their methods can return in advance of the work being completed. This\nallows them to avoid blocking overall execution of the Node.js application.

\n

N-API provides an ABI-stable interface for these\nsupporting functions which covers the most common asynchronous use cases.

\n

N-API defines the napi_async_work structure which is used to manage\nasynchronous workers. Instances are created/deleted with\nnapi_create_async_work and napi_delete_async_work.

\n

The execute and complete callbacks are functions that will be\ninvoked when the executor is ready to execute and when it completes its\ntask respectively.

\n

The execute function should avoid making any N-API calls\nthat could result in the execution of JavaScript or interaction with\nJavaScript objects. Most often, any code that needs to make N-API\ncalls should be made in complete callback instead.\nAvoid using the napi_env parameter in the execute callback as\nit will likely execute JavaScript.

\n

These functions implement the following interfaces:

\n
typedef void (*napi_async_execute_callback)(napi_env env,\n                                            void* data);\ntypedef void (*napi_async_complete_callback)(napi_env env,\n                                             napi_status status,\n                                             void* data);\n
\n

When these methods are invoked, the data parameter passed will be the\naddon-provided void* data that was passed into the\nnapi_create_async_work call.

\n

Once created the async worker can be queued\nfor execution using the napi_queue_async_work function:

\n
napi_status napi_queue_async_work(napi_env env,\n                                  napi_async_work work);\n
\n

napi_cancel_async_work can be used if the work needs\nto be cancelled before the work has started execution.

\n

After calling napi_cancel_async_work, the complete callback\nwill be invoked with a status value of napi_cancelled.\nThe work should not be deleted before the complete\ncallback invocation, even when it was cancelled.

", "modules": [ { "textRaw": "napi_create_async_work", "name": "napi_create_async_work", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [ { "version": "v8.6.0", "pr-url": "https://github.com/nodejs/node/pull/14697", "description": "Added `async_resource` and `async_resource_name` parameters." } ] }, "desc": "
napi_status napi_create_async_work(napi_env env,\n                                   napi_value async_resource,\n                                   napi_value async_resource_name,\n                                   napi_async_execute_callback execute,\n                                   napi_async_complete_callback complete,\n                                   void* data,\n                                   napi_async_work* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API allocates a work object that is used to execute logic asynchronously.\nIt should be freed using napi_delete_async_work once the work is no longer\nrequired.

\n

async_resource_name should be a null-terminated, UTF-8-encoded string.

\n

The async_resource_name identifier is provided by the user and should be\nrepresentative of the type of async work being performed. It is also recommended\nto apply namespacing to the identifier, e.g. by including the module name. See\nthe async_hooks documentation for more information.

", "type": "module", "displayName": "napi_create_async_work" }, { "textRaw": "napi_delete_async_work", "name": "napi_delete_async_work", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_delete_async_work(napi_env env,\n                                   napi_async_work work);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API frees a previously allocated work object.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_delete_async_work" }, { "textRaw": "napi_queue_async_work", "name": "napi_queue_async_work", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_queue_async_work(napi_env env,\n                                  napi_async_work work);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API requests that the previously allocated work be scheduled\nfor execution. Once it returns successfully, this API must not be called again\nwith the same napi_async_work item or the result will be undefined.

", "type": "module", "displayName": "napi_queue_async_work" }, { "textRaw": "napi_cancel_async_work", "name": "napi_cancel_async_work", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_cancel_async_work(napi_env env,\n                                   napi_async_work work);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API cancels queued work if it has not yet\nbeen started. If it has already started executing, it cannot be\ncancelled and napi_generic_failure will be returned. If successful,\nthe complete callback will be invoked with a status value of\nnapi_cancelled. The work should not be deleted before the complete\ncallback invocation, even if it has been successfully cancelled.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_cancel_async_work" } ], "type": "misc", "displayName": "Simple asynchronous operations" }, { "textRaw": "Custom asynchronous operations", "name": "custom_asynchronous_operations", "desc": "

The simple asynchronous work APIs above may not be appropriate for every\nscenario. When using any other asynchronous mechanism, the following APIs\nare necessary to ensure an asynchronous operation is properly tracked by\nthe runtime.

", "modules": [ { "textRaw": "napi_async_init", "name": "napi_async_init", "meta": { "added": [ "v8.6.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_async_init(napi_env env,\n                            napi_value async_resource,\n                            napi_value async_resource_name,\n                            napi_async_context* result)\n
\n\n

Returns napi_ok if the API succeeded.

", "type": "module", "displayName": "napi_async_init" }, { "textRaw": "napi_async_destroy", "name": "napi_async_destroy", "meta": { "added": [ "v8.6.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_async_destroy(napi_env env,\n                               napi_async_context async_context);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_async_destroy" }, { "textRaw": "napi_make_callback", "name": "napi_make_callback", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [ { "version": "v8.6.0", "description": "Added `async_context` parameter." } ] }, "desc": "
NAPI_EXTERN napi_status napi_make_callback(napi_env env,\n                                           napi_async_context async_context,\n                                           napi_value recv,\n                                           napi_value func,\n                                           size_t argc,\n                                           const napi_value* argv,\n                                           napi_value* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This method allows a JavaScript function object to be called from a native\nadd-on. This API is similar to napi_call_function. However, it is used to call\nfrom native code back into JavaScript after returning from an async\noperation (when there is no other script on the stack). It is a fairly simple\nwrapper around node::MakeCallback.

\n

Note it is not necessary to use napi_make_callback from within a\nnapi_async_complete_callback; in that situation the callback's async\ncontext has already been set up, so a direct call to napi_call_function\nis sufficient and appropriate. Use of the napi_make_callback function\nmay be required when implementing custom async behavior that does not use\nnapi_create_async_work.

\n

Any process.nextTicks or Promises scheduled on the microtask queue by\nJavaScript during the callback are ran before returning back to C/C++.

", "type": "module", "displayName": "napi_make_callback" }, { "textRaw": "napi_open_callback_scope", "name": "napi_open_callback_scope", "meta": { "added": [ "v9.6.0" ], "napiVersion": [ 3 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_open_callback_scope(napi_env env,\n                                                 napi_value resource_object,\n                                                 napi_async_context context,\n                                                 napi_callback_scope* result)\n
\n\n

There are cases (for example, resolving promises) where it is\nnecessary to have the equivalent of the scope associated with a callback\nin place when making certain N-API calls. If there is no other script on\nthe stack the napi_open_callback_scope and\nnapi_close_callback_scope functions can be used to open/close\nthe required scope.

", "type": "module", "displayName": "napi_open_callback_scope" }, { "textRaw": "napi_close_callback_scope", "name": "napi_close_callback_scope", "meta": { "added": [ "v9.6.0" ], "napiVersion": [ 3 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_close_callback_scope(napi_env env,\n                                                  napi_callback_scope scope)\n
\n\n

This API can be called even if there is a pending JavaScript exception.

", "type": "module", "displayName": "napi_close_callback_scope" } ], "type": "misc", "displayName": "Custom asynchronous operations" }, { "textRaw": "Version management", "name": "version_management", "modules": [ { "textRaw": "napi_get_node_version", "name": "napi_get_node_version", "meta": { "added": [ "v8.4.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
typedef struct {\n  uint32_t major;\n  uint32_t minor;\n  uint32_t patch;\n  const char* release;\n} napi_node_version;\n\nnapi_status napi_get_node_version(napi_env env,\n                                  const napi_node_version** version);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This function fills the version struct with the major, minor, and patch\nversion of Node.js that is currently running, and the release field with the\nvalue of process.release.name.

\n

The returned buffer is statically allocated and does not need to be freed.

", "type": "module", "displayName": "napi_get_node_version" }, { "textRaw": "napi_get_version", "name": "napi_get_version", "meta": { "added": [ "v8.0.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_get_version(napi_env env,\n                             uint32_t* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API returns the highest N-API version supported by the\nNode.js runtime. N-API is planned to be additive such that\nnewer releases of Node.js may support additional API functions.\nIn order to allow an addon to use a newer function when running with\nversions of Node.js that support it, while providing\nfallback behavior when running with Node.js versions that don't\nsupport it:

\n", "type": "module", "displayName": "napi_get_version" } ], "type": "misc", "displayName": "Version management" }, { "textRaw": "Memory management", "name": "memory_management", "modules": [ { "textRaw": "napi_adjust_external_memory", "name": "napi_adjust_external_memory", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_adjust_external_memory(napi_env env,\n                                                    int64_t change_in_bytes,\n                                                    int64_t* result);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This function gives V8 an indication of the amount of externally allocated\nmemory that is kept alive by JavaScript objects (i.e. a JavaScript object\nthat points to its own memory allocated by a native module). Registering\nexternally allocated memory will trigger global garbage collections more\noften than it would otherwise.

", "type": "module", "displayName": "napi_adjust_external_memory" } ], "type": "misc", "displayName": "Memory management" }, { "textRaw": "Promises", "name": "promises", "desc": "

N-API provides facilities for creating Promise objects as described in\nSection 25.4 of the ECMA specification. It implements promises as a pair of\nobjects. When a promise is created by napi_create_promise(), a \"deferred\"\nobject is created and returned alongside the Promise. The deferred object is\nbound to the created Promise and is the only means to resolve or reject the\nPromise using napi_resolve_deferred() or napi_reject_deferred(). The\ndeferred object that is created by napi_create_promise() is freed by\nnapi_resolve_deferred() or napi_reject_deferred(). The Promise object may\nbe returned to JavaScript where it can be used in the usual fashion.

\n

For example, to create a promise and pass it to an asynchronous worker:

\n
napi_deferred deferred;\nnapi_value promise;\nnapi_status status;\n\n// Create the promise.\nstatus = napi_create_promise(env, &deferred, &promise);\nif (status != napi_ok) return NULL;\n\n// Pass the deferred to a function that performs an asynchronous action.\ndo_something_asynchronous(deferred);\n\n// Return the promise to JS\nreturn promise;\n
\n

The above function do_something_asynchronous() would perform its asynchronous\naction and then it would resolve or reject the deferred, thereby concluding the\npromise and freeing the deferred:

\n
napi_deferred deferred;\nnapi_value undefined;\nnapi_status status;\n\n// Create a value with which to conclude the deferred.\nstatus = napi_get_undefined(env, &undefined);\nif (status != napi_ok) return NULL;\n\n// Resolve or reject the promise associated with the deferred depending on\n// whether the asynchronous action succeeded.\nif (asynchronous_action_succeeded) {\n  status = napi_resolve_deferred(env, deferred, undefined);\n} else {\n  status = napi_reject_deferred(env, deferred, undefined);\n}\nif (status != napi_ok) return NULL;\n\n// At this point the deferred has been freed, so we should assign NULL to it.\ndeferred = NULL;\n
", "modules": [ { "textRaw": "napi_create_promise", "name": "napi_create_promise", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_create_promise(napi_env env,\n                                napi_deferred* deferred,\n                                napi_value* promise);\n
\n\n

Returns napi_ok if the API succeeded.

\n

This API creates a deferred object and a JavaScript promise.

", "type": "module", "displayName": "napi_create_promise" }, { "textRaw": "napi_resolve_deferred", "name": "napi_resolve_deferred", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_resolve_deferred(napi_env env,\n                                  napi_deferred deferred,\n                                  napi_value resolution);\n
\n\n

This API resolves a JavaScript promise by way of the deferred object\nwith which it is associated. Thus, it can only be used to resolve JavaScript\npromises for which the corresponding deferred object is available. This\neffectively means that the promise must have been created using\nnapi_create_promise() and the deferred object returned from that call must\nhave been retained in order to be passed to this API.

\n

The deferred object is freed upon successful completion.

", "type": "module", "displayName": "napi_resolve_deferred" }, { "textRaw": "napi_reject_deferred", "name": "napi_reject_deferred", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_reject_deferred(napi_env env,\n                                 napi_deferred deferred,\n                                 napi_value rejection);\n
\n\n

This API rejects a JavaScript promise by way of the deferred object\nwith which it is associated. Thus, it can only be used to reject JavaScript\npromises for which the corresponding deferred object is available. This\neffectively means that the promise must have been created using\nnapi_create_promise() and the deferred object returned from that call must\nhave been retained in order to be passed to this API.

\n

The deferred object is freed upon successful completion.

", "type": "module", "displayName": "napi_reject_deferred" }, { "textRaw": "napi_is_promise", "name": "napi_is_promise", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
napi_status napi_is_promise(napi_env env,\n                            napi_value value,\n                            bool* is_promise);\n
\n", "type": "module", "displayName": "napi_is_promise" } ], "type": "misc", "displayName": "Promises" }, { "textRaw": "Script execution", "name": "script_execution", "desc": "

N-API provides an API for executing a string containing JavaScript using the\nunderlying JavaScript engine.

", "modules": [ { "textRaw": "napi_run_script", "name": "napi_run_script", "meta": { "added": [ "v8.5.0" ], "napiVersion": [ 1 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_run_script(napi_env env,\n                                        napi_value script,\n                                        napi_value* result);\n
\n\n

This function executes a string of JavaScript code and returns its result with\nthe following caveats:

\n", "type": "module", "displayName": "napi_run_script" } ], "type": "misc", "displayName": "Script execution" }, { "textRaw": "libuv event loop", "name": "libuv_event_loop", "desc": "

N-API provides a function for getting the current event loop associated with\na specific napi_env.

", "modules": [ { "textRaw": "napi_get_uv_event_loop", "name": "napi_get_uv_event_loop", "meta": { "added": [ "v8.10.0", "v9.3.0" ], "napiVersion": [ 2 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status napi_get_uv_event_loop(napi_env env,\n                                               struct uv_loop_s** loop);\n
\n", "type": "module", "displayName": "napi_get_uv_event_loop" } ], "type": "misc", "displayName": "libuv event loop" }, { "textRaw": "Asynchronous thread-safe function calls", "name": "asynchronous_thread-safe_function_calls", "desc": "

JavaScript functions can normally only be called from a native addon's main\nthread. If an addon creates additional threads, then N-API functions that\nrequire a napi_env, napi_value, or napi_ref must not be called from those\nthreads.

\n

When an addon has additional threads and JavaScript functions need to be invoked\nbased on the processing completed by those threads, those threads must\ncommunicate with the addon's main thread so that the main thread can invoke the\nJavaScript function on their behalf. The thread-safe function APIs provide an\neasy way to do this.

\n

These APIs provide the type napi_threadsafe_function as well as APIs to\ncreate, destroy, and call objects of this type.\nnapi_create_threadsafe_function() creates a persistent reference to a\nnapi_value that holds a JavaScript function which can be called from multiple\nthreads. The calls happen asynchronously. This means that values with which the\nJavaScript callback is to be called will be placed in a queue, and, for each\nvalue in the queue, a call will eventually be made to the JavaScript function.

\n

Upon creation of a napi_threadsafe_function a napi_finalize callback can be\nprovided. This callback will be invoked on the main thread when the thread-safe\nfunction is about to be destroyed. It receives the context and the finalize data\ngiven during construction, and provides an opportunity for cleaning up after the\nthreads e.g. by calling uv_thread_join(). Aside from the main loop thread,\nno threads should be using the thread-safe function after the finalize callback\ncompletes.

\n

The context given during the call to napi_create_threadsafe_function() can\nbe retrieved from any thread with a call to\nnapi_get_threadsafe_function_context().

", "modules": [ { "textRaw": "Calling a thread-safe function", "name": "calling_a_thread-safe_function", "desc": "

napi_call_threadsafe_function() can be used for initiating a call into\nJavaScript. napi_call_threadsafe_function() accepts a parameter which controls\nwhether the API behaves blockingly. If set to napi_tsfn_nonblocking, the API\nbehaves non-blockingly, returning napi_queue_full if the queue was full,\npreventing data from being successfully added to the queue. If set to\nnapi_tsfn_blocking, the API blocks until space becomes available in the queue.\nnapi_call_threadsafe_function() never blocks if the thread-safe function was\ncreated with a maximum queue size of 0.

\n

napi_call_threadsafe_function() should not be called with napi_tsfn_blocking\nfrom a JavaScript thread, because, if the queue is full, it may cause the\nJavaScript thread to deadlock.

\n

The actual call into JavaScript is controlled by the callback given via the\ncall_js_cb parameter. call_js_cb is invoked on the main thread once for each\nvalue that was placed into the queue by a successful call to\nnapi_call_threadsafe_function(). If such a callback is not given, a default\ncallback will be used, and the resulting JavaScript call will have no arguments.\nThe call_js_cb callback receives the JavaScript function to call as a\nnapi_value in its parameters, as well as the void* context pointer used when\ncreating the napi_threadsafe_function, and the next data pointer that was\ncreated by one of the secondary threads. The callback can then use an API such\nas napi_call_function() to call into JavaScript.

\n

The callback may also be invoked with env and call_js_cb both set to NULL\nto indicate that calls into JavaScript are no longer possible, while items\nremain in the queue that may need to be freed. This normally occurs when the\nNode.js process exits while there is a thread-safe function still active.

\n

It is not necessary to call into JavaScript via napi_make_callback() because\nN-API runs call_js_cb in a context appropriate for callbacks.

", "type": "module", "displayName": "Calling a thread-safe function" }, { "textRaw": "Reference counting of thread-safe functions", "name": "reference_counting_of_thread-safe_functions", "desc": "

Threads can be added to and removed from a napi_threadsafe_function object\nduring its existence. Thus, in addition to specifying an initial number of\nthreads upon creation, napi_acquire_threadsafe_function can be called to\nindicate that a new thread will start making use of the thread-safe function.\nSimilarly, napi_release_threadsafe_function can be called to indicate that an\nexisting thread will stop making use of the thread-safe function.

\n

napi_threadsafe_function objects are destroyed when every thread which uses\nthe object has called napi_release_threadsafe_function() or has received a\nreturn status of napi_closing in response to a call to\nnapi_call_threadsafe_function. The queue is emptied before the\nnapi_threadsafe_function is destroyed. napi_release_threadsafe_function()\nshould be the last API call made in conjunction with a given\nnapi_threadsafe_function, because after the call completes, there is no\nguarantee that the napi_threadsafe_function is still allocated. For the same\nreason, do not make use of a thread-safe function\nafter receiving a return value of napi_closing in response to a call to\nnapi_call_threadsafe_function. Data associated with the\nnapi_threadsafe_function can be freed in its napi_finalize callback which\nwas passed to napi_create_threadsafe_function(). The parameter\ninitial_thread_count of napi_create_threadsafe_function marks the initial\nnumber of aquisitions of the thread-safe functions, instead of calling\nnapi_acquire_threadsafe_function multiple times at creation.

\n

Once the number of threads making use of a napi_threadsafe_function reaches\nzero, no further threads can start making use of it by calling\nnapi_acquire_threadsafe_function(). In fact, all subsequent API calls\nassociated with it, except napi_release_threadsafe_function(), will return an\nerror value of napi_closing.

\n

The thread-safe function can be \"aborted\" by giving a value of napi_tsfn_abort\nto napi_release_threadsafe_function(). This will cause all subsequent APIs\nassociated with the thread-safe function except\nnapi_release_threadsafe_function() to return napi_closing even before its\nreference count reaches zero. In particular, napi_call_threadsafe_function()\nwill return napi_closing, thus informing the threads that it is no longer\npossible to make asynchronous calls to the thread-safe function. This can be\nused as a criterion for terminating the thread. Upon receiving a return value\nof napi_closing from napi_call_threadsafe_function() a thread must make no\nfurther use of the thread-safe function because it is no longer guaranteed to\nbe allocated.

", "type": "module", "displayName": "Reference counting of thread-safe functions" }, { "textRaw": "Deciding whether to keep the process running", "name": "deciding_whether_to_keep_the_process_running", "desc": "

Similarly to libuv handles, thread-safe functions can be \"referenced\" and\n\"unreferenced\". A \"referenced\" thread-safe function will cause the event loop on\nthe thread on which it is created to remain alive until the thread-safe function\nis destroyed. In contrast, an \"unreferenced\" thread-safe function will not\nprevent the event loop from exiting. The APIs napi_ref_threadsafe_function and\nnapi_unref_threadsafe_function exist for this purpose.

\n

Neither does napi_unref_threadsafe_function mark the thread-safe functions as\nable to be destroyed nor does napi_ref_threadsafe_function prevent it from\nbeing destroyed.

", "type": "module", "displayName": "Deciding whether to keep the process running" }, { "textRaw": "napi_create_threadsafe_function", "name": "napi_create_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [ { "version": [ "v12.6.0", "v10.17.0" ], "pr-url": "https://github.com/nodejs/node/pull/27791", "description": "Made `func` parameter optional with custom `call_js_cb`." } ] }, "desc": "
NAPI_EXTERN napi_status\nnapi_create_threadsafe_function(napi_env env,\n                                napi_value func,\n                                napi_value async_resource,\n                                napi_value async_resource_name,\n                                size_t max_queue_size,\n                                size_t initial_thread_count,\n                                void* thread_finalize_data,\n                                napi_finalize thread_finalize_cb,\n                                void* context,\n                                napi_threadsafe_function_call_js call_js_cb,\n                                napi_threadsafe_function* result);\n
\n", "type": "module", "displayName": "napi_create_threadsafe_function" }, { "textRaw": "napi_get_threadsafe_function_context", "name": "napi_get_threadsafe_function_context", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\nnapi_get_threadsafe_function_context(napi_threadsafe_function func,\n                                     void** result);\n
\n\n

This API may be called from any thread which makes use of func.

", "type": "module", "displayName": "napi_get_threadsafe_function_context" }, { "textRaw": "napi_call_threadsafe_function", "name": "napi_call_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [ { "version": "v14.5.0", "pr-url": "https://github.com/nodejs/node/pull/33453", "description": "Support for `napi_would_deadlock` has been reverted.\n" }, { "version": "v14.1.0", "pr-url": "https://github.com/nodejs/node/pull/32689", "description": "Return `napi_would_deadlock` when called with `napi_tsfn_blocking` from the main thread or a worker thread and the queue is full.\n" } ] }, "desc": "
NAPI_EXTERN napi_status\nnapi_call_threadsafe_function(napi_threadsafe_function func,\n                              void* data,\n                              napi_threadsafe_function_call_mode is_blocking);\n
\n\n

This API should not be called with napi_tsfn_blocking from a JavaScript\nthread, because, if the queue is full, it may cause the JavaScript thread to\ndeadlock.

\n

This API will return napi_closing if napi_release_threadsafe_function() was\ncalled with abort set to napi_tsfn_abort from any thread. The value is only\nadded to the queue if the API returns napi_ok.

\n

This API may be called from any thread which makes use of func.

", "type": "module", "displayName": "napi_call_threadsafe_function" }, { "textRaw": "napi_acquire_threadsafe_function", "name": "napi_acquire_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\nnapi_acquire_threadsafe_function(napi_threadsafe_function func);\n
\n\n

A thread should call this API before passing func to any other thread-safe\nfunction APIs to indicate that it will be making use of func. This prevents\nfunc from being destroyed when all other threads have stopped making use of\nit.

\n

This API may be called from any thread which will start making use of func.

", "type": "module", "displayName": "napi_acquire_threadsafe_function" }, { "textRaw": "napi_release_threadsafe_function", "name": "napi_release_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\nnapi_release_threadsafe_function(napi_threadsafe_function func,\n                                 napi_threadsafe_function_release_mode mode);\n
\n\n

A thread should call this API when it stops making use of func. Passing func\nto any thread-safe APIs after having called this API has undefined results, as\nfunc may have been destroyed.

\n

This API may be called from any thread which will stop making use of func.

", "type": "module", "displayName": "napi_release_threadsafe_function" }, { "textRaw": "napi_ref_threadsafe_function", "name": "napi_ref_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\nnapi_ref_threadsafe_function(napi_env env, napi_threadsafe_function func);\n
\n\n

This API is used to indicate that the event loop running on the main thread\nshould not exit until func has been destroyed. Similar to uv_ref it is\nalso idempotent.

\n

Neither does napi_unref_threadsafe_function mark the thread-safe functions as\nable to be destroyed nor does napi_ref_threadsafe_function prevent it from\nbeing destroyed. napi_acquire_threadsafe_function and\nnapi_release_threadsafe_function are available for that purpose.

\n

This API may only be called from the main thread.

", "type": "module", "displayName": "napi_ref_threadsafe_function" }, { "textRaw": "napi_unref_threadsafe_function", "name": "napi_unref_threadsafe_function", "meta": { "added": [ "v10.6.0" ], "napiVersion": [ 4 ], "changes": [] }, "desc": "
NAPI_EXTERN napi_status\nnapi_unref_threadsafe_function(napi_env env, napi_threadsafe_function func);\n
\n\n

This API is used to indicate that the event loop running on the main thread\nmay exit before func is destroyed. Similar to uv_unref it is also\nidempotent.

\n

This API may only be called from the main thread.

", "type": "module", "displayName": "napi_unref_threadsafe_function" } ], "type": "misc", "displayName": "Asynchronous thread-safe function calls" } ] } ] }