module

A WebAssembly.Module object.

An array containing objects representing the exported functions of the given module.

If module is not a WebAssembly.Module object instance, a TypeError is thrown.

The following example (see our index-compile.html demo on GitHub, and view it live also) compiles the loaded simple.wasm byte code using the WebAssembly.compileStreaming() method and then sends it to a worker using postMessage().

const worker = new Worker("wasm_worker.js");

WebAssembly.compileStreaming(fetch('simple.wasm'))
  .then((mod) => worker.postMessage(mod));

In the worker (see wasm_worker.js) we define an import object for the module to use, then set up an event handler to receive the module from the main thread. when the module is received, we create an instance from it using the WebAssembly.Instantiate() method, invoke an exported function from inside it, then show how we can return information on the available exports on a module using WebAssembly.Module.exports.

const importObject = {
  imports: {
    imported_func(arg) {
      console.log(arg);
    },
  },
};

onmessage = (e) => {
  console.log('module received from main thread');
  const mod = e.data;

  WebAssembly.instantiate(mod, importObject).then((instance) => {
    instance.exports.exported_func();
  });

  const exports = WebAssembly.Module.exports(mod);
  console.log(exports[0]);
};

The exports[0] output looks like this:

{ name: "exported_func", kind: "function" }

• WebAssembly overview page
• WebAssembly concepts
• Using the WebAssembly JavaScript API