⚙️ WebAssembly

​Bindings

WebAssembly modules are bound as follows. The bound keys will be instances of WebAssembly.ModuleOpen external link:

Using the CLICLI
Using wrangler.tomlwrangler.toml
Using the APIJavaScript API
$ miniflare --wasm MODULE1=module1.wasm --wasm MODULE2=module2.wasm
wrangler.toml
[wasm_modules]
MODULE1 = "module1.wasm"
MODULE2 = "module2.wasm"
const mf = new Miniflare({
  wasmBindings: {
    MODULE1: "module1.wasm",
    MODULE2: "module2.wasm",
  },
});

You can then use the WebAssembly modules in your workers:

const instance = new WebAssembly.Instance(MODULE1);

addEventListener("fetch", (e) => {
  // Assuming MODULE1 exports a function `add` summing 2 integer arguments
  const value = instance.exports.add(1, 2);
  e.respondWith(new Response(value.toString()));
});

​Modules

You can also import WebAssembly modules by adding a CompiledWasm module rule. See 📚 Modules for more details. For instance, with the following wrangler.toml file and worker script, we can achieve the same result as the previous example:

wrangler.toml
[[build.upload.rules]]
type = "CompiledWasm"
globs = ["**/*.wasm"]

import module1 from "./module1.wasm";

const instance = new WebAssembly.Instance(module1);

export default {
  fetch() {
    const value = instance.exports.add(1, 2);
    return new Response(value.toString());
  },
};

​Rust Wrangler Builds

When using Rust Wrangler Builds, wasm is automatically bound to your compiled WebAssembly module.