napi-rs

This project was initialized from xray

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

Platform Support

Operating Systems

Linux	macOS	Windows MSVC	FreeBSD
✓	✓	✓	✓

NodeJS

Node10	Node12	Node14	Node15
✓	✓	✓	✓

This library depends on N-API and requires Node@10.0.0 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/JavaScript toolchain and without involving node-gyp.

Taste

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()?;
  ctx.env.create_int64(fibonacci_native(n))
}

#[inline(always)]
fn fibonacci_native(n: i64) -> i64 {
  match n {
    1 | 2 => 1,
    _ => fibonacci_native(n - 1) + fibonacci_native(n - 2),
  }
}

Register module

#[macro_use]
extern crate napi_derive;

use napi::{JsObject, Result};

/// `exports` is `module.exports` object in NodeJS
#[module_exports]
fn init(mut exports: JsObject) -> Result<()> {
  exports.create_named_method("fibonacci", fibonacci)?;
  Ok(())
}

And you can also create JavaScript value while registering module:

#[macro_use]
extern crate napi_derive;

use napi::{JsObject, Result, Env};

#[module_exports]
fn init(mut exports: JsObject, env: Env) -> Result<()> {
  exports.create_named_method("fibonacci", fibonacci)?;
  exports.set_named_property("DEFAULT_VALUE", env.create_int64(100)?)?;
  Ok(())
}

Building

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.

[package]
name = "awesome"

[lib]
crate-type = ["cdylib"]

[dependencies]
napi = "1.0"
napi-derive = "1.0"

[build-dependencies]
napi-build = "1.0"

And create build.rs in your own project:

// build.rs
extern crate napi_build;

fn main() {
  napi_build::setup();
}

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

See the included test_module for an example add-on.

Install the @napi-rs/cli to help you build your Rust codes and copy Dynamic lib file to .node file in case you can require it in your program.

{
  "package": "awesome-package",
  "devDependencies": {
    "@napi-rs/cli": "^1.0.0"
  },
  "napi": {
    "name": "jarvis" // <----------- Config the name of native addon, or the napi command will use the name of `Cargo.toml` for the binary file name.
  },
  "scripts": {
    "build": "napi build --release",
    "build:debug": "napi build"
  }
}

Then you can require your native binding:

require('./jarvis.node')

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

xxx => ./xxx.node

xxx-yyy => ./xxx_yyy.node

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

napi build [--release] ./dll
napi build [--release] ./artifacts

There are documents which contains more details about the @napi-rs/cli usage.

Testing

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	✅