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 onactivate property of the ServiceWorkerGlobalScope interface is an event handler fired whenever an activate event occurs (when the service worker activates). This happens after installation, when the page to be controlled by the service worker refreshes.


ServiceWorkerGlobalScope.onactivate = function(event) { ... };
ServiceWorkerGlobalScope.addEventListener('activate', function(event) { ... });


The following snippet comes from Using Service Workers; go there for more details.

then.addEventListener('activate', function(event) {
  var cacheWhitelist = ['v2'];

    caches.forEach(function(cache, cacheName) {
      if (cacheWhitelist.indexOf(cacheName) == -1) {
        return caches.delete(cacheName);


Specification Status Comment
Service Workers
The definition of 'Event Handlers' in that specification.
Working Draft Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 40.0 44.0 (44.0)[1] No support ? 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 40.0

[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 onactivate Property Reference Service ServiceWorker ServiceWorkerGlobalScope Workers