CacheStorage.open()

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

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
});

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

Browser compatibility

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

See also

• Using Service Workers
• Cache
• WorkerGlobalScope.caches