How to Call JavaScript from Rust in WASM

You call JavaScript from Rust in WASM by exporting a Rust function with #[wasm_bindgen] and invoking it via window in the browser.

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn greet(name: &str) -> String {
    format!("Hello, {}!", name)
}

<script>
  import init, { greet } from './pkg/my_wasm.js';
  init().then(() => {
    console.log(greet('World'));
  });
</script>

Calling JavaScript from Rust in WASM lets your high-performance Rust code run inside a web browser and talk to JavaScript. You mark a Rust function to be visible to the web, then call it just like any other JavaScript function. Think of it as a bridge where Rust does the heavy lifting and JavaScript handles the user interface.