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 keys
()
method of the CacheStorage
interface returns a Promise
that will resolve with an array containing strings corresponding to all of the named Cache
objects tracked by the CacheStorage
object in the order they were created. Use this method to iterate over a list of all Cache
objects.
Syntax
caches.keys().then(function(keyList) { //do something with your keyList });
Returns
a Promise
that resolves to an array of the Cache
names inside the CacheStorage
object.
Parameters
None.
Examples
In this code snippet we wait for an activate
event, and then run a waitUntil()
block that clears up any old, unused caches before a new service worker is activated. Here we have a whitelist containing the names of the caches we want to keep. We return the keys of the caches in the CacheStorage
object using keys()
, then check each key to see if it is in the whitelist. If not, we delete it using CacheStorage.delete
.
then.addEventListener('activate', function(event) { var cacheWhitelist = ['v2']; event.waitUntil( caches.keys().then(function(keyList) { return Promise.all(keyList.map(function(key) { if (cacheWhitelist.indexOf(key) === -1) { return caches.delete(key); } }); }) ); });
Specifications
Specification | Status | Comment |
---|---|---|
Service Workers The definition of 'CacheStorage' in that specification. |
Working Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 40.0 | 44 (44)[1] | No support | ? | No support |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | No support | No support | 44.0 (44) | (Yes) | (Yes) | (Yes) | 40.0 |
[1] Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR.)