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 claim() method of the of the Clients interface allows an active Service Worker to set itself as the active worker for a client page when the worker and the page are in the same scope. This triggers an oncontrollerchange event on any client pages within the Service Worker's scope.

This method can be used with ServiceWorkerGlobalScope.skipWaiting() to ensure that updates to the underlying service worker take effect immediately for both the current client and all other active clients.


ServiceWorkerClients.claim().then(function() {
  // Do something






The following example uses claim() inside a Service Worker's onActivate event handler so that a client page loaded in the same scope does not need to be reloaded before it can use the Service Worker.

self.addEventListener('install', function(event) {
self.addEventListener('activate', function(event) {


Specification Status Comment
Service Workers
The definition of 'Clients' in that specification.
Working Draft Initial definition. It is still under development (see issue 414 and issue 423).

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 42.0 44.0 (44.0)[1] No support 24 No support
Feature Android Firefox Mobile (Gecko) Firefox OS IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support ? 44.0 (44.0) (Yes) No support ? No support ?

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

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API claim Clients Experimental Method Reference Service Workers ServiceWorker