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

The Cache interface provides a storage mechanism for Request / Response object pairs that are cached, for example as part of the ServiceWorker life cycle. Note that the Cache interface is exposed to windowed scopes as well as workers. You don't have to use it in conjunction with service workers, even though it is defined in the service worker spec.

An origin can have multiple, named Cache objects. You are responsible for implementing how your script (e.g. in a ServiceWorker)  handles Cache updates. Items in a Cache do not get updated unless explicitly requested; they don’t expire unless deleted. Use CacheStorage.open() to open a specific named Cache object and then call any of the Cache methods to maintain the Cache.

You are also responsible for periodically purging cache entries. Each browser has a hard limit on the amount of cache storage that a given origin can use. Cache quota usage estimates are available via the StorageEstimate API. The browser does its best to manage disk space, but it may delete the Cache storage for an origin.  The browser will generally delete all of the data for an origin or none of the data for an origin. Make sure to version caches by name and use the caches only from the version of the script that they can safely operate on. See Deleting old caches for more information.

Note: Initial Cache implementations (in both Blink and Gecko) resolve Cache.add(), Cache.addAll(), and Cache.put() promises when the response body is fully written to storage.  More recent versions of the specification state that the browser can resolve the promise as soon as the entry is recorded in the database even if the response body is still streaming in.

Note: The key matching algorithm depends on the VARY header in the value. So matching a new key requires looking at both key and value for entries in the Cache.

Note: The caching API doesn't honor HTTP caching headers.

Methods

Cache.match(request, options)
Returns a Promise that resolves to the response associated with the first matching request in the Cache object.
Cache.matchAll(request, options)
Returns a Promise that resolves to an array of all matching requests in the Cache object.
Cache.add(request)
Takes a URL, retrieves it and adds the resulting response object to the given cache. This is functionally equivalent to calling fetch(), then using put() to add the results to the cache.
Cache.addAll(requests)
Takes an array of URLs, retrieves them, and adds the resulting response objects to the given cache.
Cache.put(request, response)
Takes both a request and its response and adds it to the given cache.
Cache.delete(request, options)
Finds the Cache entry whose key is the request, returning a Promise that resolves to true if a matching Cache entry is found and deleted. If no Cache entry is found, the promise resolves to false.
Cache.keys(request, options)
Returns a Promise that resolves to an array of Cache keys.

Examples

This code snippet is from the service worker selective caching sample. (see selective caching live) The code uses CacheStorage.open() to open any Cache objects with a Content-Type header that starts with "font/".

The code then uses Cache.match() to see if there's already a matching font in the cache, and if so, returns it. If there isn't a matching font, the code fetches the font from the network and uses Cache.put() to cache the fetched resource.

The code handles exceptions thrown from the fetch() 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.

The code snippet also shows a best practice for versioning caches used by the service worker. Though there's only one cache in this example, the same approach can be used for multiple caches. It maps a shorthand identifier for a cache to a specific, versioned cache name. The code also deletes all caches that aren't named in CURRENT_CACHES.

In the code example, "caches" is an attribute of the service worker's WorkerGlobalScope. It holds the CacheStorage object, by which by can access the CacheStorage interface.

Note: In Chrome, visit chrome://inspect/#service-workers and click on the "inspect" link below the registered service worker to view logging statements for the various actions the service-worker.js script is performing.
var CACHE_VERSION = 1;

// Shorthand identifier mapped to specific versioned cache.
var CURRENT_CACHES = {
  font: 'font-cache-v' + CACHE_VERSION
};

self.addEventListener('activate', function(event) {
  var expectedCacheNames = Object.values(CURRENT_CACHES);

  // Active worker won't be treated as activated until promise
  // resolves successfully.
  event.waitUntil(
    caches.keys().then(function(cacheNames) {
      return Promise.all(
        cacheNames.map(function(cacheName) {
          if (!expectedCacheNames.includes(cacheName)) {
            console.log('Deleting out of date cache:', cacheName);
            
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
});

self.addEventListener('fetch', function(event) {
  console.log('Handling fetch event for', event.request.url);

  event.respondWith(
    
    // Opens Cache objects that start with 'font'.
    caches.open(CURRENT_CACHES['font']).then(function(cache) {
      return cache.match(event.request).then(function(response) {
        if (response) {
          console.log('Found response in cache:', response);

          return response;
        }

        console.log('Fetching request from the network');

        return fetch(event.request).then(function(networkResponse) {
          cache.put(event.request, networkResponse.clone());

          return networkResponse;
        });
      }).catch(function(error) {
        
        // Handles exceptions that arise from match() or fetch().
        console.error('Error in fetch handler:', error);

        throw error;
      });
    })
  );
});

Specifications

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

Browser compatibility

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support431 Yes392 No303 No
add44416392 No315 No
addAll46616392 No336 No
delete4316392 No30 No
keys4316392 No30 No
match4316392 No30 No
matchAll4716392 No346 No
put43416392 No305 No
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support431431 No39303 No4.0
add444444 No39315 No4.0
addAll466466 No39336 No5.0
delete4343 No3930 No4.0
keys4343 No3930 No4.0
match4343 No3930 No4.0
matchAll4747 No3934 No5.0
put434434 No39305 No4.0

1. From 40 to 42, this was only available on service workers.

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

3. From 27 to 29, this was only available on service workers.

4. Requires HTTPS from version 46.

5. Requires HTTPS from version 33.

6. Requires HTTPS.

See also

Document Tags and Contributors

Last updated by: Brettz9,