# `wasm-bindgen`
**Facilitating high-level interactions between wasm modules and JavaScript.**
[Introduction blog post: "JavaScript to Rust and Back Again: A `wasm-bindgen` Tale"][post]
[host]: https://github.com/WebAssembly/host-bindings
[post]: https://hacks.mozilla.org/2018/04/javascript-to-rust-and-back-again-a-wasm-bindgen-tale/
[](https://travis-ci.org/rustwasm/wasm-bindgen)
[](https://ci.appveyor.com/project/alexcrichton/wasm-bindgen)
[](https://crates.io/crates/wasm-bindgen)
[](https://crates.io/crates/wasm-bindgen)
[](https://docs.rs/wasm-bindgen)
Import JavaScript things into Rust and export Rust things to JavaScript.
`src/lib.rs`:
```rust
#![feature(use_extern_macros)]
extern crate wasm_bindgen;
use wasm_bindgen::prelude::*;
// Import the `window.alert` function from the Web.
#[wasm_bindgen]
extern {
fn alert(s: &str);
}
// Export a `greet` function from Rust to JavaScript, that alerts a
// hello message.
#[wasm_bindgen]
pub fn greet(name: &str) {
alert(&format!("Hello, {}!", name));
}
```
Use exported Rust things from JavaScript!
`index.js`:
```js
// Asynchronously load, compile, and import the Rust's WebAssembly
// and JavaScript interface.
import("./hello_world").then(module => {
// Alert "Hello, World!"
module.greet("World!");
});
```
## Guide
[📚 Read the `wasm-bindgen` guide here! 📚](https://rustwasm.github.io/wasm-bindgen)
## License
This project is licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
http://www.apache.org/licenses/LICENSE-2.0)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or
http://opensource.org/licenses/MIT)
at your option.
## Contribution
**[See the "Contributing" section of the guide for information on
hacking on `wasm-bindgen`!][contributing]**
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this project by you, as defined in the Apache-2.0 license,
shall be dual licensed as above, without any additional terms or conditions.
[contributing]: https://rustwasm.github.io/wasm-bindgen/contributing.html