ServiceWorkerGlobalScope: activate event

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is only available in Service Workers.

The activate event of the ServiceWorkerGlobalScope interface is fired when a ServiceWorkerRegistration acquires a new ServiceWorkerRegistration.active worker.

This event is not cancelable and does not bubble.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

js
addEventListener("activate", (event) => { })

onactivate = (event) => { }

Event type

An ExtendableEvent. Inherits from Event.

EventExtendableEvent

Examples

The following snippet shows how you could use an activate event handler to upgrade a cache.

js
self.addEventListener("activate", (event) => {
  const cacheAllowlist = ["v2"];

  event.waitUntil(
    caches.keys().then((cacheNames) =>
      Promise.all(
        cacheNames.map((cacheName) => {
          if (!cacheAllowlist.includes(cacheName)) {
            return caches.delete(cacheName);
          }
          return undefined;
        }),
      ),
    ),
  );
});

You can also set up the event handler using the onactivate property:

js
self.onactivate = (event) => {
  // …
};

Specifications

See also