W3cubDocs

/JavaScript

WebAssembly.module

A WebAssembly.Module object contains stateless WebAssembly code that has already been compiled by the browser — this can be efficiently shared with Workers, and instantiated multiple times.

Constructor

WebAssembly.Module()
Creates a new Module object.

Static properties

WebAssembly.Module.customSections()
Given a Module and string, returns a copy of the contents of all custom sections in the module with the given string name.
WebAssembly.Module.exports()
Given a Module, returns an array containing descriptions of all the declared exports.
WebAssembly.Module.imports()
Given a Module, returns an array containing descriptions of all the declared imports.

Examples

Sending a compiled module to a worker

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 the resulting Module instance to a worker using postMessage().

var 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 and invoke an exported function from inside it.

var importObject = {
  imports: {
    imported_func: function(arg) {
      console.log(arg);
    }
  }
};

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

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

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
Module 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
Module() constructor 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
customSections 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
exports 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
imports 57 16 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
No 44 11
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Module 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
Module() constructor 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
customSections 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
exports 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
imports 57 57 52
52
Disabled in the Firefox 52 Extended Support Release (ESR).
43 11 7.0
Server
Node.js
Module 8.0.0
Module() constructor 8.0.0
customSections 8.0.0
exports 8.0.0
imports 8.0.0

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/Module