- Easy: Just write idiomatic Rust code, node-bindgen take care of generating Node.js FFI wrapper codes.
- Safe: Node.js arguments are checked automatically based on Rust types.
- Async: Support Async Rust. Async codes are translated into Node.js promises.
- Class: Rust struct can be accessed using Node.js classes.
- Stream: Implement Node.js stream using Rust
- N-API: Use Node.js N-API, which means you don't have to recompile your module.
This project uses the v8 of Node N-API. Please see following compatibility matrix.
Following OS are supported:
- Linux
- MacOs
- Windows
Writing native node-js requires lots of boilerplate code. Node-bindgen generates external "C" glue code from rust code, including native module registration. node-bindgen make it writing node-js module easy and fun.
Install nj-cli command line, which will be used to generate the native library.
cargo install nj-cli
This is a one time step.
Add two dependencies to your projects' Cargo.toml
.
Add node-bindgen
as a regular dependency (as below):
[dependencies]
node-bindgen = { version = "6.0" }
Then add node-bindgen
's procedure macro to your build-dependencies as below:
[build-dependencies]
node-bindgen = { version = "6.0", default-features = false, features = ["build"] }
Then update crate type to cdylib
to generate node.js compatible native module:
[lib]
crate-type = ["cdylib"]
Finally, add build.rs
at the top of the project with following content:
fn main() {
node_bindgen::build::configure();
}
Here is a function that adds two numbers. Note that you don't need to worry about JS conversion.
use node_bindgen::derive::node_bindgen;
/// add two integer
#[node_bindgen]
fn sum(first: i32, second: i32) -> i32 {
first + second
}
To build node.js library, using nj-cli
to build:
nj-cli build
This will generate Node.js module in "./dist" folder.
To build a release version:
nj-cli build --release
While developing your native module, you may want to watch for file changes and run a command when a change occurs, for example cargo check
or cargo build
.
For this, we can use nj-cli watch
.
nj-cli watch
installs [if it does not exist] and passes arguments to cargo watch
. By default, nj-cli watch
will run cargo check
against your ./src
files.
To see all available methods for nj-cli watch
, run the following command:
nj-cli watch -- --help
Then in the Node.js, rust function can be invoked as normal node.js function:
$ node
Welcome to Node.js v18.18.0.
Type ".help" for more information.
> let addon = require('./dist');
undefined
> addon.sum(2,3)
5
>
#[node_bindgen(name="multiply")]
fn mul(first: i32,second: i32) -> i32 {
first * second
}
Rust function mul is re-mapped as multiply
Argument can be skipped if it is marked as optional
#[node_bindgen]
fn sum(first: i32, second: Option<i32>) -> i32 {
first + second.unwrap_or(0)
}
Then sum can be invoked as
sum(10)
or sum(10,20)
JS callback are mapped as Rust closure.
#[node_bindgen]
fn hello<F: Fn(String)>(first: f64, second: F) {
let msg = format!("argument is: {}", first);
second(msg);
}
from node:
let addon = require('./dist');
addon.hello(2,function(msg){
assert.equal(msg,"argument is: 2");
console.log(msg); // print out argument is 2
});
Callback are supported in Async rust as well.
Async rust function is mapped to Node.js promise.
use std::time::Duration;
use flv_future_aio::time::sleep;
use node_bindgen::derive::node_bindgen;
#[node_bindgen]
async fn hello(arg: f64) -> f64 {
println!("sleeping");
sleep(Duration::from_secs(1)).await;
println!("woke and adding 10.0");
arg + 10.0
}
let addon = require('./dist');
addon.hello(5).then((val) => {
console.log("future value is %s",val);
});
Structs, including generic structs, can have have the to-JS conversion boilerplate autogenerated.
Just apply the node_bindgen
macro to your struct:
#[node_bindgen]
struct MyJson {
some_name: String,
a_number: i64
}
#[node_bindgen]
fn my_json() -> MyJson {
MyJson {
some_name: "John".to_owned(),
a_number: 1337
}
}
let addon = require('./dist');
assert.deepStrictEqual(addon.my_json(), {
someName: "John",
aNumber: 1337
});
Note that the fields must implement
node_bindgen::core::TryIntoJs
themselves.
Any references must also implement Clone
.
Field names will be converted to camelCase.
Enums will also have their JS representation autogenerated with the help of node_bindgen
:
#[node_bindgen]
enum ErrorType {
WithMessage(String, usize),
WithFields {
val: usize
},
UnitErrorType
}
#[node_bindgen]
fn with_message() -> ErrorType {
ErrorType::WithMessage("test".to_owned(), 321)
}
#[node_bindgen]
fn with_fields() -> ErrorType {
ErrorType::WithFields {
val: 123
}
}
#[node_bindgen]
fn with_unit() -> ErrorType {
ErrorType::UnitErrorType
}
assert.deepStrictEqual(addon.withMessage(), {
withMessage: ["test", 321n]
});
assert.deepStrictEqual(addon.withFields(), {
withFields: {
val: 123n
}
});
assert.deepStrictEqual(addon.withUnit(), "UnitErrorType")
Tuple variants will be converted into lists, struct variants converted to objects, and unit variants converted into strings matching the variant's name in PascalCase. Generics and references are supported, with the same caveats as for structs.
JavaScript class is supported.
struct MyClass {
val: f64,
}
#[node_bindgen]
impl MyClass {
#[node_bindgen(constructor)]
fn new(val: f64) -> Self {
Self { val }
}
#[node_bindgen]
fn plus_one(&self) -> f64 {
self.val + 1.0
}
#[node_bindgen(getter)]
fn value(&self) -> f64 {
self.val
}
}
let addon = require('./dist');
const assert = require('assert');
let obj = new addon.MyObject(10);
assert.equal(obj.value,10,"verify value works");
assert.equal(obj.plusOne(),11);
There are more features in the examples folder.
When using node-bindgen with electron on Windows, nj-build
must
compile a C++ file, win_delay_load_hook.cc
, and therefore it is required that the development
environment has a valid C/C++ compiler.
If your machine does not have a valid C/C++ compiler, install Microsoft VSCode.
In the future, this file will be re-written in Rust, removing this dependency.
Just make sure that you are compiling the rust module using
npx electron-build-env nj-cli build --release
otherwise you will get dreaded A dynamic link library (DLL) initialization routine failed
when importing the rust module in electron
Node module generated with node-bindgen
can be used directly in any node JS project, just copied index.node
into it. But in case of direct access to a module IDE will not highlight available functions, classes etc. Usually, this is not comfortable and makes the risks of potential bugs higher as soon as the public API of the node module is changed.
To create a full-fledged npm package with TypeScript types definitions and all necessary JavaScript wrappers can be used a crate tslink.
tslink
crate generates files *.d.ts
, *.js
and package.json
with a description of the npm module. Such package could be integrated into an end-project with minimal effort.
In addition, because tslink
generates TypeScript types definitions, any changes on the native node module (index.node
) will be highlighted by TypeScript
compiler and it makes the risk of bugs (related to changed API or public data types) much lower.
For example,
#[macro_use] extern crate tslink;
use tslink::tslink;
use node_bindgen::derive::node_bindgen;
struct MyScruct {
inc: i32,
}
#[tslink(class)]
#[node_bindgen]
impl MyScruct {
#[tslink(constructor)]
#[node_bindgen(constructor)]
pub fn new(inc: i32) -> Self {
Self { inc }
}
#[tslink(snake_case_naming)]
#[node_bindgen]
fn inc_my_number(&self, a: i32) -> i32 {
a + self.inc
}
}
Would be represented (*.d.ts
) as
export declare class MyStruct {
constructor(inc: number);
incMyNumber(a: number): number;
}
Pay your attention, call of #[tslink]
should be always above of call #[node_bindgen]
.
Also, please note, node-bindgen
by default applies snake case naming to methods. You should use #[tslink(snake_case_naming)]
to consider this moment (see more on crate page).
tslink
requires a configuration in Cargo.toml
(section [tslink]
) of the root of your project. A configuration should include a valid path to the native node module. By default node-bindgen
creates index.node
in ./dist
folder of your root
.
File: ./Cargo.toml
(in a root
of project):
[project]
# ...
[lib]
# ...
[tslink]
node = "./dist/index.node"
Full example of usage tslink
and node-bindgen
is here.
See more API documentation on a tslink
crate page.
Note. The node-bindgen's developers are not responsible for the correctness of the work tslink crate. All possible issues and feature requests related to tslink should be addressed to tslink's developers.
If you'd like to contribute to the project, please read our Contributing guide.
This project is licensed under the Apache license.