ServiceWorkerGlobalScope
Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ServiceWorkerGlobalScope
interface of the ServiceWorker API (en-US) 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
(en-US).
Additionally, synchronous requests are not allowed from within a service worker — only asynchronous requests, like those initiated via the fetch()
(en-US) method, can be used.
This interface inherits from the WorkerGlobalScope
(en-US) interface, and its parent EventTarget
, and therefore implements properties from WindowTimers
, WindowBase64
, and WindowEventHandlers
.
Properties
ServiceWorkerGlobalScope.clients
읽기 전용-
Contains the
Clients
object associated with the service worker. ServiceWorkerGlobalScope.registration
(en-US) 읽기 전용-
Contains the
ServiceWorkerRegistration
object that represents the service worker's registration. ServiceWorkerGlobalScope.caches
(en-US) 읽기 전용-
Contains the
CacheStorage
(en-US) object associated with the service worker.
Events
activate
-
Occurs when a
ServiceWorkerRegistration
acquires a newServiceWorkerRegistration.active
worker. Also available via theServiceWorkerGlobalScope.onactivate
property. fetch
-
Occurs when a
fetch()
(en-US) is called. Also available via theServiceWorkerGlobalScope.onfetch
property. install
-
Occurs when a
ServiceWorkerRegistration
acquires a newServiceWorkerRegistration.installing
worker. Also available via theServiceWorkerGlobalScope.oninstall
property. message
-
Occurs when incoming messages are received. Controlled pages can use the
MessagePort.postMessage()
(en-US) method to send messages to service workers. The service worker can optionally send a response back via theMessagePort
(en-US) exposed inevent.data.port
, corresponding to the controlled page. Also available via theServiceWorkerGlobalScope.onmessage
(en-US) 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. 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. sync
-
Triggered when a call to
SyncManager.register
(en-US) 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 theServiceWorkerGlobalScope.onsync
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
(en-US) — which implements WindowOrWorkerGlobalScope
. Therefore it also has the following property available to it:
GlobalFetch.fetch()
(en-US)-
Starts the process of fetching a resource. This returns a promise that resolves to the
Response
(en-US) 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()
(en-US) 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;
});
})
);
});
명세서
Specification |
---|
Service Workers # serviceworkerglobalscope-interface |
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