0.3.10 • Public • Published


This project was initialized from xray

A minimal library for building compiled NodeJS add-ons in Rust.

Platform Support

Lint Linux N-API@3 Linux musl macOS/Windows/Linux x64 Linux-aarch64 Windows i686 FreeBSD

Operating Systems

Linux macOS Windows MSVC FreeBSD


Node10 Node 12 Node14

This library depends on N-API and requires Node@8.9 or later.

We already have some packages written by napi-rs: node-rs

One nice feature is that this crate allows you to build add-ons purely with the Rust toolchain and without involving node-gyp.


You can start from package-template to play with napi-rs

Define JavaScript functions

#[js_function(1)] // ------> arguments length, omit for zero
fn fibonacci(ctx: CallContext) -> Result<JsNumber> {
  let n = ctx.get::<JsNumber>(0)?.try_into()?;
fn fibonacci_native(n: i64) -> i64 {
  match n {
    1 | 2 => 1,
    _ => fibonacci_native(- 1+ fibonacci_native(- 2),

Register module

/// test_module is Module name
register_module!(test_module, init);
/// Module is `module` object in NodeJS
fn init(module: &mut Module) -> Result<()> {
  module.create_named_method("fibonacci", fibonacci)?;


This repository is a Cargo crate. Any napi-based add-on should contain Cargo.toml to make it a Cargo crate.

In your Cargo.toml you need to set the crate-type to "cdylib" so that cargo builds a C-style shared library that can be dynamically loaded by the Node executable. You'll also need to add this crate as a dependency.

crate-type = ["cdylib"]
napi = "0.5"
napi-derive = "0.5"
napi-build = "0.2"

And create in your own project:

extern crate napi_build;
fn main() {

So far, the napi build script has only been tested on macOS Linux and Windows x64 MSVC.

See the included test_module for an example add-on.

Run cargo build to produce the Dynamic lib file. And install the napi-rs to help you copy Dynamic lib file to .node file in case you can require it in your program.

  "package": "your pkg",
  "devDependencies": {
    "napi-rs": "latest"
  "scripts": {
    "build": "cargo build && napi build",
    "build-release": "cargo build --release && napi build --release"

Then you can require your native binding:


The module_name would be your package name in your Cargo.toml.

xxx => ./target/debug|release/xxx.node

xxx-yyy => ./target/debug|release/xxx_yyy.node

You can also copy Dynamic lib file to an appointed location:

napi build [--release] .
napi build [--release] ./mylib


Because libraries that depend on this crate must be loaded into a Node executable in order to resolve symbols, all tests are written in JavaScript in the test_module subdirectory.

To run tests:

yarn build:test
yarn test

Features table

Create JavaScript values

NAPI NAPI Version Minimal Node version Status
napi_create_array 1 v8.0.0
napi_create_array_with_length 1 v8.0.0
napi_create_arraybuffer 1 v8.0.0
napi_create_buffer 1 v8.0.0
napi_create_buffer_copy 1 v8.0.0
napi_create_date 5 v11.11.0
napi_create_external 1 v8.0.0
napi_create_external_arraybuffer 1 v8.0.0
napi_create_external_buffer 1 v8.0.0
napi_create_object 1 v8.0.0
napi_create_symbol 1 v8.0.0
napi_create_typedarray 1 v8.0.0
napi_create_dataview 1 v8.3.0
napi_create_int32 1 v8.4.0
napi_create_uint32 1 v8.4.0
napi_create_int64 1 v8.4.0
napi_create_double 1 v8.4.0
napi_create_bigint_int64 6 v10.7.0
napi_create_bigint_uint64 6 v10.7.0
napi_create_bigint_words 6 v10.7.0
napi_create_string_latin1 1 v8.0.0
napi_create_string_utf16 1 v8.0.0
napi_create_string_utf8 1 v8.0.0

Functions to convert from N-API to C types

NAPI NAPI Version Minimal Node Version Status
napi_get_array_length 1 v8.0.0
napi_get_arraybuffer_info 1 v8.0.0
napi_get_buffer_info 1 v8.0.0
napi_get_prototype 1 v8.0.0
napi_get_typedarray_info 1 v8.0.0
napi_get_dataview_info 1 v8.3.0
napi_get_date_value 5 v11.11.0
napi_get_value_bool 1 v8.0.0
napi_get_value_double 1 v8.0.0
napi_get_value_bigint_int64 6 v10.7.0
napi_get_value_bigint_uint64 6 v10.7.0
napi_get_value_bigint_words 6 v10.7.0
napi_get_value_external 1 v8.0.0
napi_get_value_int32 1 v8.0.0
napi_get_value_int64 1 v8.0.0
napi_get_value_string_latin1 1 v8.0.0
napi_get_value_string_utf8 1 v8.0.0
napi_get_value_string_utf16 1 v8.0.0
napi_get_value_uint32 1 v8.0.0
napi_get_boolean 1 v8.0.0
napi_get_global 1 v8.0.0
napi_get_null 1 v8.0.0
napi_get_undefined 1 v8.0.0

Working with JavaScript Values and Abstract Operations

NAPI NAPI Version Minimal Node Version Status
napi_coerce_to_bool 1 v8.0.0
napi_coerce_to_number 1 v8.0.0
napi_coerce_to_object 1 v8.0.0
napi_coerce_to_string 1 v8.0.0
napi_typeof 1 v8.0.0
napi_instanceof 1 v8.0.0
napi_is_array 1 v8.0.0
napi_is_arraybuffer 1 v8.0.0
napi_is_buffer 1 v8.0.0
napi_is_date 1 v8.0.0
napi_is_error 1 v8.0.0
napi_is_typedarray 1 v8.0.0
napi_is_dataview 1 v8.3.0
napi_strict_equals 1 v8.0.0
napi_detach_arraybuffer 7 v13.3.0
napi_is_detached_arraybuffer 7 v13.3.0




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