SharedWorker
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).
Note: In Firefox, shared workers cannot be shared between private (i.e. browsing in a private window) and non-private documents (see bug 1177621.)
Properties
Inherits properties from its parent, EventTarget
, and implements properties from AbstractWorker
.
AbstractWorker.onerror
- Is an
EventListener
that is called whenever anErrorEvent
of typeerror
bubbles through the worker. SharedWorker.port
Read only- Returns a
MessagePort
object used to communicate and control the shared worker.
Constructors
SharedWorker()
- Creates a shared web worker that executes the script at the specified URL.
Methods
Inherits methods from its parent, EventTarget
, and implements properties 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
Specification | Status | Comment |
---|---|---|
WHATWG HTML Living Standard The definition of 'SharedWorker' in that specification. |
Living Standard | No change from Web Workers. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Support | 4 | 29.0 (29.0) | No support | 10.60 | 5 No support 6.1 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Support | No support | No support | 33.0 (33.0) | 2.1 | No support | 11.5 | 5.1 No support 7.1 |
See also
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/sharedworker