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CacheStorage: has() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨April 2018⁩.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

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 Window.caches property in windows or through the WorkerGlobalScope.caches property in workers.

Syntax

has(cacheName)

Parameters

cacheName: A string 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((hasCache) => {
    if (!hasCache) {
      someCacheSetupFunction();
    } else {
      caches.open("v1").then((cache) => cache.addAll(myAssets));
    }
  })
  .catch(() => {
    // Handle exception here.
  });

Specifications

Specification
Service Workers> # cache-storage-has>

Browser compatibility

	Desktop					Mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	WebView on iOS
`has`	40	16	41	27	11.1	40	41	27	11.3	4.0	40	11.3