The node-addon-api package is a helper library for building Node.js Addons in C++. It provides a C++ API that abstracts away the complexities of working with the low-level V8 and N-API provided by Node.js, making it easier to develop native addons.

What are node-addon-api's main functionalities?

Object Wrapping

Object wrapping allows C++ classes to be represented as JavaScript objects. It provides an easy way to create and manage objects that have a one-to-one relationship with C++ objects.

Napi::ObjectReference MyClass::constructor;

MyClass::MyClass(const Napi::CallbackInfo& info) : Napi::ObjectWrap<MyClass>(info) {
  // constructor implementation
}

Napi::Object MyClass::Init(Napi::Env env, Napi::Object exports) {
  Napi::HandleScope scope(env);

  Napi::Function func = DefineClass(env, "MyClass", {
    InstanceMethod("myMethod", &MyClass::MyMethod)
  });

  constructor = Napi::Persistent(func);
  constructor.SuppressDestruct();

  exports.Set("MyClass", func);
  return exports;
}

Function Arguments

The package provides a way to handle function arguments passed from JavaScript to C++ with type checking and conversion utilities.

Napi::Value MyFunction(const Napi::CallbackInfo& info) {
  Napi::Env env = info.Env();
  if (info.Length() < 2) {
    Napi::TypeError::New(env, "Expected at least two arguments").ThrowAsJavaScriptException();
  }

  Napi::String arg0 = info[0].As<Napi::String>();
  double arg1 = info[1].As<Napi::Number>().DoubleValue();

  // function implementation

  return Napi::String::New(env, "result");
}

Asynchronous Operations

node-addon-api provides utilities for performing asynchronous operations, allowing long-running tasks to be executed without blocking the Node.js event loop.

class MyAsyncWorker : public Napi::AsyncWorker {
public:
  MyAsyncWorker(Napi::Function& callback) : AsyncWorker(callback) {}

  void Execute() override {
    // Do work in another thread
  }

  void OnOK() override {
    Napi::HandleScope scope(Env());
    Callback().Call({Env().Null(), Napi::String::New(Env(), "Success")});
  }
};

Napi::Value RunAsyncWork(const Napi::CallbackInfo& info) {
  Napi::Function callback = info[0].As<Napi::Function>();
  MyAsyncWorker* worker = new MyAsyncWorker(callback);
  worker->Queue();
  return info.Env().Undefined();
}

Other packages similar to node-addon-api

Changelog

Source

2022-05-02 Version 5.0.0, @NickNaso

Notable changes:

API

Marked methods of wrapper classes const.
Enabled wrapping Napi namespace with custom namespace.
Added an override to Napi::Function::Call to call it with a c-style array of Napi::Value's.
Some other minor fixes.

TEST

Improved the test framework. Added the possibility to run subsets of tests more easily.
Added test for Napi::AsyncContext class.
Fixed ramdom failure on test for Napi::ThreadSafeFunction e Napi::TypedThreadSafeFunction class.
Fixed compilation problem on debian 8 system.
Added test for Napi::Object::Set() method.

Documentation

Added some clarifications for Napi::ClassPropertyDescriptor.
Added clarification about weak reference for Napi::ObjectWrap.
Some minor fixes all over the documentation.

TOOL

Fixed eslint configuration.
Fixed CI configuration for Windows.
Enabled pre-commit ClangFormat on Windows.

Commits

[f32db917f3] - Add test coverage for async contexts (#1164) (Jack)
[24455f88af] - src: check for tsfn in conditional_variable wait (Kevin Eady) #1168
[40ed7ce409] - src: fix regression introduced by #874 (Michael Dawson)
[9bea434326] - doc: added some comments to ClassPropertyDescriptor. (#1149) (Nicola Del Gobbo)
[57c212e15f] - buld: Enable running pre-commit ClangFormat on Win (Vladimir Morozov)
[8c46a9501a] - doc: clarify ObjectWrap weak ref behavior (#1155) (Alba Mendez)
[01274966d5] - build: run Windows CI only on nondeprecated build configurations (#1152) (Darshan Sen)
[b8449e17e0] - src: mark methods of wrapper classes const (Nikolai Vavilov) #874
[5e2c1f24f8] - lint: set sourceType to 'script' (#1141) (Anna Henningsen)
[da8af20152] - doc: mention Napi::Env arg for Finalization callback (#1139) (extremeheat)
[5b51864a39] - src: enable wrapping Napi namespace with custom namespace (#1135) (Anna Henningsen)
[c54aeef5fd] - Add Function::Call Napi::Value override (#1026) (rgerd)
[e906b5a7ce] - test: fix compilation problem on debian 8 (NickNaso) #1138
[5790c55784] - src: do not use non-static class member for constant value (#1134) (Anna Henningsen)
[b7659db945] - Merge pull request #1130 from meixg/main (Jack)
[a840d51d21] - Add test case for Object Set using uint32 as key (meixg)
[2c88a7ec4c] - Merge pull request #1132 from JckXia/test-wfl-run (Jack)
[d3a5ed3869] - Revert "window CI to running on 2019" (JckXia)
[cee899ade5] - src: allow customization of ObjectWrap behavior (Aaron Meriwether) #1125
[91879b4082] - remove window-latest to debug (JckXia)
[1593ef46ee] - Testing CI run (JckXia)
[744c8d2410] - test: enhance the test framework (Deepak Rajamohan)

Readme

Source

NOTE: The default branch has been renamed! master is now named main

If you have a local clone, you can update it by running:

git branch -m master main
git fetch origin
git branch -u origin/main main

node-addon-api module

This module contains header-only C++ wrapper classes which simplify the use of the C based Node-API provided by Node.js when using C++. It provides a C++ object model and exception handling semantics with low overhead.

There are three options for implementing addons: Node-API, nan, or direct use of internal V8, libuv and Node.js libraries. Unless there is a need for direct access to functionality which is not exposed by Node-API as outlined in C/C++ addons in Node.js core, use Node-API. Refer to C/C++ addons with Node-API for more information on Node-API.

Node-API is an ABI stable C interface provided by Node.js for building native addons. It is independent from the underlying JavaScript runtime (e.g. V8 or ChakraCore) and is maintained as part of Node.js itself. It is intended to insulate native addons from changes in the underlying JavaScript engine and allow modules compiled for one version to run on later versions of Node.js without recompilation.

The node-addon-api module, which is not part of Node.js, preserves the benefits of the Node-API as it consists only of inline code that depends only on the stable API provided by Node-API. As such, modules built against one version of Node.js using node-addon-api should run without having to be rebuilt with newer versions of Node.js.

It is important to remember that other Node.js interfaces such as libuv (included in a project via #include <uv.h>) are not ABI-stable across Node.js major versions. Thus, an addon must use Node-API and/or node-addon-api exclusively and build against a version of Node.js that includes an implementation of Node-API (meaning an active LTS version of Node.js) in order to benefit from ABI stability across Node.js major versions. Node.js provides an ABI stability guide containing a detailed explanation of ABI stability in general, and the Node-API ABI stability guarantee in particular.

As new APIs are added to Node-API, node-addon-api must be updated to provide wrappers for those new APIs. For this reason node-addon-api provides methods that allow callers to obtain the underlying Node-API handles so direct calls to Node-API and the use of the objects/methods provided by node-addon-api can be used together. For example, in order to be able to use an API for which the node-addon-api does not yet provide a wrapper.

APIs exposed by node-addon-api are generally used to create and manipulate JavaScript values. Concepts and operations generally map to ideas specified in the ECMA262 Language Specification.

The Node-API Resource offers an excellent orientation and tips for developers just getting started with Node-API and node-addon-api.

Setup
API Documentation
Examples
Tests
More resource and info about native Addons
Badges
Code of Conduct
Contributors
License

Current version: 5.0.0

(See CHANGELOG.md for complete Changelog)

node-addon-api is based on Node-API and supports using different Node-API versions. This allows addons built with it to run with Node.js versions which support the targeted Node-API version. However the node-addon-api support model is to support only the active LTS Node.js versions. This means that every year there will be a new major which drops support for the Node.js LTS version which has gone out of service.

The oldest Node.js version supported by the current version of node-addon-api is Node.js 14.x.

Setup

API Documentation

The following is the documentation for node-addon-api.

Examples

Are you new to node-addon-api? Take a look at our examples

Tests

To run the node-addon-api tests do:

npm install
npm test

To avoid testing the deprecated portions of the API run

npm install
npm test --disable-deprecated

To run the tests targeting a specific version of Node-API run

npm install
export NAPI_VERSION=X
npm test --NAPI_VERSION=X

where X is the version of Node-API you want to target.

Debug

To run the node-addon-api tests with --debug option:

npm run-script dev

If you want faster build, you might use the following option:

npm run-script dev:incremental

Take a look and get inspired by our test suite

Benchmarks

You can run the available benchmarks using the following command:

npm run-script benchmark

See benchmark/README.md for more details about running and adding benchmarks.

More resource and info about native Addons

As node-addon-api's core mission is to expose the plain C Node-API as C++ wrappers, tools that facilitate n-api/node-addon-api providing more convenient patterns on developing a Node.js add-ons with n-api/node-addon-api can be published to NPM as standalone packages. It is also recommended to tag such packages with node-addon-api to provide more visibility to the community.

Quick links to NPM searches: keywords:node-addon-api.

Other bindings

napi-rs - (Rust)

Badges

The use of badges is recommended to indicate the minimum version of Node-API required for the module. This helps to determine which Node.js major versions are supported. Addon maintainers can consult the Node-API support matrix to determine which Node.js versions provide a given Node-API version. The following badges are available:

Node-API v1 Badge Node-API v2 Badge Node-API v3 Badge Node-API v4 Badge Node-API v5 Badge Node-API v6 Badge Node-API v7 Badge Node-API v8 Badge Node-API Experimental Version Badge

Contributing

We love contributions from the community to node-addon-api! See CONTRIBUTING.md for more details on our philosophy around extending this module.

Team members

Active

Name	GitHub Link
Anna Henningsen	addaleax
Chengzhong Wu	legendecas
Gabriel Schulhof	gabrielschulhof
Jim Schlight	jschlight
Michael Dawson	mhdawson
Kevin Eady	KevinEady
Nicola Del Gobbo	NickNaso

Emeritus

Name	GitHub Link
Arunesh Chandra	aruneshchandra
Benjamin Byholm	kkoopa
Jason Ginchereau	jasongin
Hitesh Kanwathirtha	digitalinfinity
Sampson Gao	sampsongao
Taylor Woll	boingoing

Licensed under MIT

Keywords

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Last updated on 02 May 2022

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Install

node-addon-api