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ServiceWorkerGlobalScope

The ServiceWorkerGlobalScope interface of the Service Worker API represents the global execution context of a service worker.

Developers should keep in mind that the ServiceWorker state is not persisted across the termination/restart cycle, so each event handler should assume it's being invoked with a bare, default global state.

Once successfully registered, a service worker can and will be terminated when idle to conserve memory and processor power. An active service worker is automatically restarted to respond to events, such as ServiceWorkerGlobalScope.onfetch or ServiceWorkerGlobalScope.onmessage.

Additionally, synchronous requests are not allowed from within a service worker — only asynchronous requests, like those initiated via the fetch() method, can be used.

This interface inherits from the WorkerGlobalScope interface, and its parent EventTarget.

Properties

ServiceWorkerGlobalScope.caches Read only

Contains the CacheStorage object associated with the service worker.

ServiceWorkerGlobalScope.clients Read only

Contains the Clients object associated with the service worker.

ServiceWorkerGlobalScope.registration Read only

Contains the ServiceWorkerRegistration object that represents the service worker's registration.

Events

activate

Occurs when a ServiceWorkerRegistration acquires a new ServiceWorkerRegistration.active worker. Also available via the ServiceWorkerGlobalScope.onactivate property.

contentdelete

Occurs when an item is removed from the Content Index. Also available via the ServiceWorkerGlobalScope.oncontentdelete property.

fetch

Occurs when a fetch() is called. Also available via the ServiceWorkerGlobalScope.onfetch property.

install

Occurs when a ServiceWorkerRegistration acquires a new ServiceWorkerRegistration.installing worker. Also available via the ServiceWorkerGlobalScope.oninstall property.

message

Occurs when incoming messages are received. Controlled pages can use the MessagePort.postMessage() method to send messages to service workers. The service worker can optionally send a response back via the MessagePort exposed in event.data.port, corresponding to the controlled page. Also available via the ServiceWorkerGlobalScope.onmessage property.

notificationclick

Occurs when a user clicks on a displayed notification. Also available via the ServiceWorkerGlobalScope.onnotificationclick property.

notificationclose

Occurs — when a user closes a displayed notification. Also available via the ServiceWorkerGlobalScope.onnotificationclose property.

sync

Triggered when a call to SyncManager.register is made from a service worker client page. The attempt to sync is made either immediately if the network is available or as soon as the network becomes available. Also available via the ServiceWorkerGlobalScope.onsync property.

periodicsync

Occurs at periodic intervals, which were specified when registering a PeriodicSyncManager. Also available via the ServiceWorkerGlobalScope.onperiodicsync property.

push

Occurs when a server push notification is received. Also available via the ServiceWorkerGlobalScope.onpush property.

pushsubscriptionchange

Occurs when a push subscription has been invalidated, or is about to be invalidated (e.g. when a push service sets an expiration time). Also available via the ServiceWorkerGlobalScope.onpushsubscriptionchange property.

Methods

ServiceWorkerGlobalScope.skipWaiting()

Allows the current service worker registration to progress from waiting to active state while service worker clients are using it.

ServiceWorkerGlobalScope implements WorkerGlobalScope. Therefore it also has the following property available to it:

fetch()

Starts the process of fetching a resource. This returns a promise that resolves to the Response object representing the response to your request. This algorithm is the entry point for the fetch handling handed to the service worker context.

Examples

This code snippet is from the service worker prefetch sample (see prefetch example live.) The ServiceWorkerGlobalScope.onfetch event handler listens for the fetch event. When fired, the code returns a promise that resolves to the first matching request in the Cache object. If no match is found, the code fetches a response from the network.

The code also handles exceptions thrown from the fetch() operation. Note that an HTTP error response (e.g., 404) will not trigger an exception. It will return a normal response object that has the appropriate error code set.

self.addEventListener('fetch', function(event) {
  console.log('Handling fetch event for', event.request.url);

  event.respondWith(
    caches.match(event.request).then(function(response) {
      if (response) {
        console.log('Found response in cache:', response);

        return response;
      }
      console.log('No response found in cache. About to fetch from network...');

      return fetch(event.request).then(function(response) {
        console.log('Response from network is:', response);

        return response;
      }, function(error) {
        console.error('Fetching failed:', error);

        throw error;
      });
    })
  );
});

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
ServiceWorkerGlobalScope
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
activate_event
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
clients
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
cookieStore
87
87
No
No
73
No
87
87
No
No
No
14.0
install_event
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
message_event
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
notificationclick_event
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
No
No
40
44
27
No
4.0
onabortpayment
70
79
No
No
?
No
No
70
No
?
No
No
onactivate
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
onbackgroundfetchabort
74
79
No
No
62
No
No
74
No
53
No
11.0
onbackgroundfetchclick
74
79
No
No
62
No
No
74
No
53
No
11.0
onbackgroundfetchfail
74
79
No
No
62
No
No
74
No
53
No
11.0
onbackgroundfetchsuccess
74
79
No
No
62
No
No
74
No
53
No
11.0
oncanmakepayment
70
79
No
No
57
No
No
70
No
49
No
10.0
oncontentdelete
No
No
No
No
No
No
84
84
No
60
No
14.0
oncookiechange
87
87
No
No
73
No
87
87
No
No
No
14.0
onfetch
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
oninstall
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
onmessage
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
11.1
40
40
44
24
11.3
4.0
onmessageerror
81
81
65
No
68
11.1
Although the onmessageerror property is supported, the messageerror event is never fired. See bug 171216.
81
81
65
58
11.3
Although the onmessageerror property is supported, the messageerror event is never fired. See bug 171216.
13.0
onnotificationclick
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
No
40
40
44
24
No
4.0
onnotificationclose
50
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
34
No
50
50
44
34
No
5.0
onpaymentrequest
70
79
No
No
?
No
No
70
No
?
No
No
onperiodicsync
80
80
No
No
67
No
No
80
No
57
No
13.0
onpush
42
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
26
No
42
42
44
26
No
4.0
onpushsubscriptionchange
No
17-79
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
No
No
No
No
44
No
No
No
onsync
49
79
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
No
49
49
44
24
No
5.0
periodicsync_event
80
80
No
No
67
No
No
80
No
57
No
13.0
push_event
40
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
24
No
40
40
44
24
No
4.0
pushsubscriptionchange_event
No
17-79
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
No
No
No
No
44
No
No
No
registration
42
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
26
11.1
42
42
44
26
11.3
4.0
serviceWorker
79
79
No
No
66
No
79
79
No
57
No
12.0
skipWaiting
41
17
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
25
11.1
41
41
44
25
11.3
4.0

See also

© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerGlobalScope