Web/API/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

Specification	Status	Comment
Service WorkersThe definition of 'CacheStorage: has' in that specification.	Working Draft	Initial definition.

Browser compatibility

Update compatibility data on GitHub

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

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
See implementation notes.': See implementation notes.