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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 open() method of the CacheStorage interface returns a Promise that resolves to the Cache object matching the cacheName.

Note: If the specified Cache does not exist, a new cache is created with that cacheName and a Promise that resolves to this new Cache object is returned.

Syntax

// "caches" is a global read-only variable, which is an instance of CacheStorage,
// For more info, refer to: https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/caches

caches.open(cacheName).then(function(cache) {
  // Do something with your cache
});

Parameters

cacheName
The name of the cache you want to open.

Return value

A Promise that resolves to the requested Cache object.

Examples

This example is from the MDN sw-test example (see sw-test running live). Here we wait for a FetchEvent to fire. Then we construct a custom response like so:

  1. Check whether a match for the request is found in the CacheStorage using CacheStorage(). If so, serve that.
  2. If not, open the v1 cache using CacheStorage.open(), put the default network request in the cache using Cache.put() and return a clone of the default network request using return response.clone(). The last is necessary because put() consumes the response body.
  3. If this fails (e.g., because the network is down), return a fallback response.
var response;
var cachedResponse = 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.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 40 44 (44)[1] No support 27 No support
Feature Android Webview Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 40 40 44.0 (44) (Yes) 27 (Yes)

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

See also

Document Tags and Contributors

 Last updated by: jpmedley,