The SharedWorker interface represents a specific kind of worker that can be accessed from several browsing contexts, such as several windows, iframes or even workers. They implement an interface different than dedicated workers and have a different global scope, SharedWorkerGlobalScope .

Note: If SharedWorker can be accessed from several browsing contexts, all those browsing contexts must share the exact same origin (same protocol, host and port).

Constructors

SharedWorker() Creates a shared web worker that executes the script at the specified URL.

Properties

Inherits properties from its parent, EventTarget , and implements properties from AbstractWorker .

AbstractWorker.onerror Is an EventListener that is called whenever an ErrorEvent of type error bubbles through the worker. SharedWorker.port Read only Returns a MessagePort object used to communicate with and control the shared worker.

Methods

Inherits methods from its parent, EventTarget , and implements methods from AbstractWorker .

Example

In our Basic shared worker example (run shared worker), we have two HTML pages, each of which uses some JavaScript to perform a simple calculation. The different scripts are using the same worker file to perform the calculation — they can both access it, even if their pages are running inside different windows.

The following code snippet shows creation of a SharedWorker object using the SharedWorker() constructor. Both scripts contain this:

var myWorker = new SharedWorker('worker.js');

Both scripts then access the worker through a MessagePort object created using the SharedWorker.port property. If the onmessage event is attached using addEventListener, the port is manually started using its start() method:

myWorker.port.start();

When the port is started, both scripts post messages to the worker and handle messages sent from it using port.postMessage() and port.onmessage , respectively:

first.onchange = function() { myWorker.port.postMessage([first.value,second.value]); console.log('Message posted to worker'); } second.onchange = function() { myWorker.port.postMessage([first.value,second.value]); console.log('Message posted to worker'); } myWorker.port.onmessage = function(e) { result1.textContent = e.data; console.log('Message received from worker'); }

Inside the worker we use the SharedWorkerGlobalScope.onconnect handler to connect to the same port discussed above. The ports associated with that worker are accessible in the connect event's ports property — we then use MessagePort start() method to start the port, and the onmessage handler to deal with messages sent from the main threads.

onconnect = function(e) { var port = e.ports[0]; port.addEventListener('message', function(e) { var workerResult = 'Result: ' + (e.data[0] * e.data[1]); port.postMessage(workerResult); }); port.start(); // Required when using addEventListener. Otherwise called implicitly by onmessage setter. }

Specifications

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub Desktop Mobile Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet SharedWorker Chrome Full support 4 Edge Full support 79 Firefox Full support 29 IE No support No Opera Full support 10.6 Safari No support 5 — 6.1 WebView Android No support No Chrome Android No support No Firefox Android Full support 33 Opera Android No support 11 — 14 Safari iOS No support 5.1 — 7 Samsung Internet Android No support 4.0 — 5.0 SharedWorker() constructor Chrome Full support 4 Edge Full support 79 Firefox Full support 29 IE No support No Opera Full support 10.6 Safari No support 5 — 6.1 WebView Android No support No Chrome Android No support No Firefox Android Full support 33 Opera Android No support 11 — 14 Safari iOS No support 5.1 — 7 Samsung Internet Android No support 4.0 — 5.0 port Chrome Full support 4 Edge Full support 79 Firefox Full support 29 IE No support No Opera Full support 10.6 Safari No support 5 — 6.1 WebView Android No support No Chrome Android No support No Firefox Android Full support 33 Opera Android No support 11 — 14 Safari iOS No support 5.1 — 7 Samsung Internet Android No support 4.0 — 5.0 Legend Full support Full support No support No support

See also