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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.

The ServiceWorkerContainer interface of the ServiceWorker API provides an object representing the service worker as an overall unit in the network ecosystem, including facilities to register, unregister and update service workers, and access the state of service workers and their registrations.

Most importantly, it exposes the ServiceWorkerContainer.register(scriptURL, scope[, base]) method used to register service workers, and the ServiceWorkerContainer.controller property used to determine whether or not the current page is actively controlled.


ServiceWorkerContainer.controller Read only
Returns a ServiceWorker object if its state is activated (the same object returned by This property returns null if the request is a force refresh (Shift + refresh) or if there is no active worker.
ServiceWorkerContainer.ready Read only
Defines whether a service worker is ready to control a page or not. It returns a Promise that will never reject, which resolves to a ServiceWorkerRegistration with an worker.

Event handlers

Fired whenever a controllerchange event occurs — when the document's associated ServiceWorkerRegistration acquires a new worker.
Fired whenever an error event occurs in the associated service workers.
Fired whenever a message event occurs — when incoming messages are received to the ServiceWorkerContainer object (e.g. via a MessagePort.postMessage() call.)


Creates or updates a ServiceWorkerRegistration for the given scriptURL.
Gets a ServiceWorkerRegistration object whose scope URL matches the provided document URL.  If the method can't return a ServiceWorkerRegistration, it returns a Promise
Returns all ServiceWorkerRegistrations associated with a ServiceWorkerContainer in an array.  If the method can't return ServiceWorkerRegistrations, it returns a Promise


This code snippet is from the service worker fallback-response sample (see fallback-response live). The code checks to see if the browser supports service workers. Then the code registers the service worker and determines if the page is actively controlled by the service worker. If it isn't, it prompts the user to reload the page so the service worker can take control. The code also reports any registration failures.

if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('service-worker.js', {scope: './'}).then(function() {
    if (navigator.serviceWorker.controller) {
      document.querySelector('#status').textContent = 'The service worker is currently handling network operations.';
    } else {
      document.querySelector('#status').textContent = 'Please reload this page to allow the service worker to handle network operations.';
  }).catch(function(error) {
    document.querySelector('#status').textContent = error;
} else {
  var aElement = document.createElement('a');
  aElement.href = '';
  aElement.textContent = 'unavailable';


Specification Status Comment
Service Workers
The definition of 'ServiceWorkerContainer' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 40 44.0 (44.0)[1] No support 24 No support
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile
Basic support No support 40 44.0 (44.0) (Yes) No support ? No support

[1] Service workers (and Push) have been disabled in the Firefox 45 and 52 Extended Support Releases (ESR.)

See also

Document Tags and Contributors

 Contributors to this page: jpmedley, jianxcao, chrisdavidmills, jsx, fscholz, Meggin
 Last updated by: jpmedley,