CacheStorage: keys() method

Syntax

keys()

Parameters

None.

Return value

A Promise that resolves with an array of the Cache names inside the CacheStorage object.

Examples

In this code snippet we wait for an activate event, and then run a waitUntil() block that clears up any old, unused caches before a new service worker is activated. Here we have an allowlist containing the names of the caches we want to keep (cacheAllowlist). We return the keys of the caches in the CacheStorage object using keys(), then check each key to see if it is in the allowlist. If not, we delete it using CacheStorage.delete().

this.addEventListener("activate", (event) => {
  const cacheAllowlist = ["v2"];

  event.waitUntil(
    caches.keys().then((keyList) =>
      Promise.all(
        keyList.map((key) => {
          if (!cacheAllowlist.includes(key)) {
            return caches.delete(key);
          }
          return undefined;
        }),
      ),
    ),
  );
});

Specifications

Browser compatibility

See also

• Using Service Workers
• Cache
• Window.caches and WorkerGlobalScope.caches