MDN will be in maintenance mode on Friday September 22nd, starting at 10 AM Pacific / 5 PM UTC, for about 1 hour.

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The WebAssembly.exports() function returns an array containing descriptions of all the declared exports of the given Module.

Syntax

var exports = WebAssembly.Module.exports(module);

Parameters

module
A WebAssembly.Module object.

Return value

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

Exceptions

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

Examples

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.compile() function and then sends it to a worker using postMessage().

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

fetch('simple.wasm').then(response =>
  response.arrayBuffer()
).then(bytes =>
  WebAssembly.compile(bytes)
).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.

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();
  });

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

The exports[0] output looks like this:

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

Specifications

Specification Status Comment
Web Assembly JavaScript API
The definition of 'exports()' in that specification.
Draft Initial draft definition.

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic Support5716522 No4411
FeatureAndroidChrome for AndroidEdge mobileFirefox for AndroidIE mobileOpera AndroidiOS Safari
Basic Support5757 (Yes)1522 No ?11

1. , this feature is behind the Experimental JavaScript Features preference.

2. Disabled in the Firefox 52 Extended Support Release (ESR).

See also

Document Tags and Contributors

 Contributors to this page: fscholz, chrisdavidmills, denimX, lukewagner, svodnik
 Last updated by: fscholz,