# `wasm-bindgen` **Facilitating high-level interactions between wasm modules and JavaScript.** [](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. ```rust 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 with ECMAScript modules! ```js import { greet } from "./hello_world"; greet("World!"); ``` ## Features * **Lightweight.** Only pay for what you use. `wasm-bindgen` only generates bindings and glue for the JavaScript imports you actually use and Rust functionality that you export. For example, importing and using the `document.querySelector` method doesn't cause `Node.prototype.appendChild` or `window.alert` to be included in the bindings as well. * **ECMAScript modules.** Just import WebAssembly modules the same way you would import JavaScript modules. Future compatible with [WebAssembly modules and ECMAScript modules integration][wasm-es-modules]. * **Designed with the ["host bindings" proposal][host-bindings] in mind.** Eventually, there won't be any JavaScript shims between Rust-generated wasm functions and native DOM methods. Because the wasm functions are statically type checked, some of those native methods' dynamic type checks should become unnecessary, promising to unlock even-faster-than-JavaScript DOM access. [wasm-es-modules]: https://github.com/WebAssembly/esm-integration [host-bindings]: https://github.com/WebAssembly/host-bindings/blob/master/proposals/host-bindings/Overview.md ## 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