This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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.


caches.keys().then(function(keyList) {
  //do something with your keyList


a Promise that resolves with an array of the Cache names inside the CacheStorage object.




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'];

    caches.keys().then(function(keyList) {
      return Promise.all(keyList.map(function(key) {
        if (cacheWhitelist.indexOf(key) === -1) {
          return caches.delete(key);


Specification Status Comment
Service Workers
The definition of 'CacheStorage: keys' in that specification.
Working Draft Initial definition.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 40 Yes 44
Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR.)
No 27 11.1
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support 40 40 Yes 44 27 Yes ?

See also

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