napi-rs

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Platform Support

Operating Systems

Linux	macOS	Windows x64 MSVC
✓	✓	✓

NodeJS

Node10	Node 12	Node14
✓	✓	✓

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

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.

Taste

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

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.

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

[dependencies]
napi = "0.4"
napi-derive = "0.4"

[build-dependencies]
napi-build = "0.2"

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 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-release": "cargo build --release && napi --release"
  }
}

Then you can require your native binding:

require('./target/debug|release/[module_name].node')

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

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 --cwd ./test_module build
yarn test

Features table

Create JavaScript values

NAPI	NAPI Version	Minimal Node version	Status
Enum types	6	v13.7.0	⛔️
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	Experimental	v13.3.0	⛔️
napi_is_detached_arraybuffer	Experimental	v13.3.0	⛔️