CacheStorage.has()

The has() method of the CacheStorage interface returns a Promise that resolves to true if a Cache object matches the cacheName.

You can access CacheStorage through the global caches property.

Syntax

caches.has(cacheName).then(function(boolean) {
  // true: your cache exists!
});

Parameters

cacheName

A DOMString representing the name of the Cache object you are looking for in the CacheStorage.

Return value

a Promise that resolves to true if the cache exists or false if not.

Examples

The following example first checks whether a cache called 'v1' exists. If so, we add a list of assets to it. If not then we run some kind of cache set-up function.

caches.has('v1').then(function(hasCache) {
  if (!hasCache) {
    someCacheSetupFunction();
  } else {
    caches.open('v1').then(function(cache) {
      return cache.addAll(myAssets);
    });
  }
}).catch(function() {
  // Handle exception here.
});

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
has
40
16
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
No
27
11.1
40
40
44
27
Yes
4.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/CacheStorage/has