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CacheStorage.open()

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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.

Syntax

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

Returns

a Promise that resolves to the requested Cache object.

Parameters

cacheName
The name of the cache you want to open.

Examples

This code snippet 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.match. 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() — 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.
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 Extended Support Release (ESR.)

See also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, jpmedley, kscarfone
 Last updated by: chrisdavidmills,