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

The CacheStorage interface represents the storage for Cache objects.

The interface:

  • provides a master directory of all the named caches that can be accessed by a ServiceWorker or other type of worker or window scope (you’re not limited to only using it with service workers, even though the Service Workers spec defines it)
  • maintains a mapping of string names to corresponding Cache objects

Use CacheStorage.open() to obtain a Cache instance.

Use CacheStorage.match() to check if a given Request is a key in any of the Cache objects that the CacheStorage object tracks.

You can access CacheStorage through the global caches property.

Note: CacheStorage always rejects with a SecurityError on untrusted origins (i.e. those that aren't using HTTPS, although this definition will likely become more complex in the future.) When testing, you can get around this by checking the "Enable Service Workers over HTTP (when toolbox is open)" option in the Firefox Devtools options/gear menu.
Note: CacheStorage.match() is a convenience method. Equivalent functionality to match a cache entry can be implemented by opening your cache with CacheStorage.open(), returning the entries it contains with CacheStorage.keys(), and matching the one you want with CacheStorage.match().

Methods

CacheStorage.match()
Checks if a given Request is a key in any of the Cache objects that the CacheStorage object tracks, and returns a Promise that resolves to that match.
CacheStorage.has()
Returns a Promise that resolves to true if a Cache object matching the cacheName exists.
CacheStorage.open()
Returns a Promise that resolves to the Cache object matching the cacheName (a new cache is created if it doesn't already exist.)
CacheStorage.delete()
Finds the Cache object matching the cacheName, and if found, deletes the Cache object and returns a Promise that resolves to true. If no Cache object is found, it returns false.
CacheStorage.keys()
Returns a Promise that will resolve with an array containing strings corresponding to all of the named Cache objects tracked by the CacheStorage. Use this method to iterate over a list of all the Cache objects.

Examples

This code snippet is from the MDN sw-test example (see sw-test running live.) This service worker script waits for an InstallEvent to fire, then runs waitUntil to handle the install process for the app. This consists of calling CacheStorage.open to create a new cache, then using Cache.addAll to add a series of assets to it.

In the second code block, we wait for a FetchEvent to fire. We construct a custom response like so:

  1. Check whether a match for the request is found in the CacheStorage. If so, serve that.
  2. If not, fetch the request from the network, then also open the cache created in the first block and add a clone of the request to it using Cache.put (cache.put(event.request, response.clone()).)
  3. If this fails (e.g. because the network is down), return a fallback response.

Finally, return whatever the custom response ended up being equal to, using FetchEvent.respondWith.

this.addEventListener('install', function(event) {
  event.waitUntil(
    caches.open('v1').then(function(cache) {
      return cache.addAll([
        '/sw-test/',
        '/sw-test/index.html',
        '/sw-test/style.css',
        '/sw-test/app.js',
        '/sw-test/image-list.js',
        '/sw-test/star-wars-logo.jpg',
        '/sw-test/gallery/bountyHunters.jpg',
        '/sw-test/gallery/myLittleVader.jpg',
        '/sw-test/gallery/snowTroopers.jpg'
      ]);
    })
  );
});

this.addEventListener('fetch', function(event) {
  var response;
  event.respondWith(caches.match(event.request).catch(function() {
    return fetch(event.request);
  }).then(function(r) {
    response = r;
    caches.open('v1').then(function(cache) {
      cache.put(event.request, response);
    });
    return response.clone();
  }).catch(function() {
    return caches.match('/sw-test/gallery/myLittleVader.jpg');
  }));
});

Specifications

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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support401 2 Yes443 No27 No
delete40 Yes443 No27 No
has40 Yes443 No27 No
keys40 Yes443 No27 No
match

54

404

Yes443 No

41

274

No
open40 Yes443 No27 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support401 2401 2 Yes4427 Yes ?
delete4040 Yes4427 Yes ?
has4040 Yes4427 Yes ?
keys4040 Yes4427 Yes ?
match

54

404

54

404

Yes44

41

274

Yes ?
open4040 Yes4427 Yes ?

1. Accessible from Window from version 43.

2. Accessible from WorkerGlobalScope from version 43.

3. Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR.)

4. The options parameter only supports ignoreSearch, and cacheName.

See also