ServiceWorkerGlobalScope

Baseline Widely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨April 2018⁩.

* Some parts of this feature may have varying levels of support.

Secure context: This feature is available only insecure contexts (HTTPS), in some or allsupporting browsers.

Note: This feature is only available inService Workers.

TheServiceWorkerGlobalScope interface of theService 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 asfetch ormessage.

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

This interface inherits from theWorkerGlobalScope interface, and its parentEventTarget.

Instance properties

This interface inherits properties from theWorkerGlobalScope interface, and its parentEventTarget.

ServiceWorkerGlobalScope.clientsRead only: Contains theClients object associated with the service worker.
ServiceWorkerGlobalScope.cookieStoreRead only: Returns a reference to theCookieStore object associated with the service worker.
ServiceWorkerGlobalScope.registrationRead only: Contains theServiceWorkerRegistration object that represents the service worker's registration.
ServiceWorkerGlobalScope.serviceWorkerRead only: Contains theServiceWorker object that represents the service worker.

Instance methods

This interface inherits methods from theWorkerGlobalScope interface, and its parentEventTarget.

ServiceWorkerGlobalScope.skipWaiting(): Allows the current service worker registration to progress from waiting to active state while service worker clients are using it.

Events

Listen to this event usingaddEventListener() or by assigning an event listener to theoneventname property of this interface.

activate: Occurs when aServiceWorkerRegistration acquires a newServiceWorkerRegistration.active worker.
backgroundfetchabortExperimental: Fired when a background fetch operation has been canceled by the user or the app.
backgroundfetchclickExperimental: Fired when the user has clicked on the UI for a background fetch operation.
backgroundfetchfailExperimental: Fired when at least one of the requests in a background fetch operation has failed.
backgroundfetchsuccessExperimental: Fired when all of the requests in a background fetch operation have succeeded.
canmakepaymentExperimental: Fired on a payment app's service worker to check whether it is ready to handle a payment. Specifically, it is fired when the merchant website calls the PaymentRequest() constructor.
contentdeleteExperimental: Occurs when an item is removed from the ContentIndex.
cookiechange: Fired when a cookie change has occurred that matches the service worker's cookie change subscription list.
fetch: Occurs when afetch() is called.
install: Occurs when aServiceWorkerRegistration acquires a newServiceWorkerRegistration.installing worker.
message: Occurs when incoming messages are received. Controlled pages can use theMessagePort.postMessage() method to send messages to service workers.
messageerror: Occurs when incoming messages can't be deserialized.
notificationclick: Occurs when a user clicks on a displayed notification.
notificationclose: Occurs when a user closes a displayed notification.
paymentrequestExperimental: Fired on a payment app when a payment flow has been initiated on the merchant website via the PaymentRequest.show() method.
sync: Triggered when a call toSyncManager.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.
periodicsyncExperimental: Occurs at periodic intervals, which were specified when registering a PeriodicSyncManager.
push: Occurs when a server push notification is received.
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).

Examples

This code snippet is from theservice worker prefetch sample (seeprefetch example live.) Theonfetch event handler listens for thefetch event. When fired, the code returns a promise that resolves to the first matching request in theCache object. If no match is found, the code fetches a response from the network.

The code also handles exceptions thrown from thefetch() 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", (event) => {  console.log("Handling fetch event for", event.request.url);  event.respondWith(    caches.match(event.request).then((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(        (response) => {          console.log("Response from network is:", response);          return response;        },        (error) => {          console.error("Fetching failed:", error);          throw error;        },      );    }),  );});