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This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
The parameter passed into the oninstall
handler, the InstallEvent
interface represents an install action that is dispatched on the ServiceWorkerGlobalScope
of a ServiceWorker
. As a child of ExtendableEvent
, it ensures that functional events such as FetchEvent
are not dispatched during installation.
This interface inherits from the ExtendableEvent
interface.
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a:hover text { fill: #0095DD; pointer-events: all;}
Constructor
InstallEvent.InstallEvent()
- Creates a new
InstallEvent
object.
Properties
Inherits properties from its ancestor, Event
.
InstallEvent.activeWorker
Read only- Returns the
ServiceWorker
that is currently actively controlling the page.
Methods
Inherits methods from its parent, ExtendableEvent
.
Examples
This code snippet is from the service worker prefetch sample (see prefetch running live.) The code calls ExtendableEvent.waitUntil(any value)
in ServiceWorkerGlobalScope.oninstall
and delays treating the ServiceWorkerRegistration.installing
worker as installed until the passed promise resolves successfully. The promise resolves when all resources have been fetched and cached, or else when any exception occurs.
The code snippet also shows a best practice for versioning caches used by the service worker. Although this example has only one cache, you can use this approach for multiple caches. The code maps a shorthand identifier for a cache to a specific, versioned cache name.
Note: Logging statements are visible in Google Chrome via the "Inspect" interface for the relevant service worker accessed via chrome://serviceworker-internals.
var CACHE_VERSION = 1; var CURRENT_CACHES = { prefetch: 'prefetch-cache-v' + CACHE_VERSION }; self.addEventListener('install', function(event) { var urlsToPrefetch = [ './static/pre_fetched.txt', './static/pre_fetched.html', 'https://www.chromium.org/_/rsrc/1302286216006/config/customLogo.gif' ]; console.log('Handling install event. Resources to pre-fetch:', urlsToPrefetch); event.waitUntil( caches.open(CURRENT_CACHES['prefetch']).then(function(cache) { cache.addAll(urlsToPrefetch.map(function(urlToPrefetch) { return new Request(urlToPrefetch, {mode: 'no-cors'}); })).then(function() { console.log('All resources have been fetched and cached.'); }); }).catch(function(error) { console.error('Pre-fetching failed:', error); }) ); });
Specifications
Specification | Status | Comment |
---|---|---|
Service Workers | Working Draft | As of May 2015, the install event is an instance of ExtendableEvent rather than a child of it. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 40.0 | 44.0 (44.0)[1] | No support | 24 | 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 Extended Support Release (ESR.)