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

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

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 and 52 Extended Support Releases (ESR.)

See also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, jpmedley, Sebastianz, kscarfone
 Last updated by: chrisdavidmills,