CacheStorage: keys() method
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 keys()
method of the CacheStorage
interface returns a Promise
that will resolve with an array containing strings corresponding to all of the named Cache
objects tracked by the CacheStorage
object in the order they were created.
Use this method to iterate over a list of all Cache
objects.
You can access CacheStorage
through the Window.caches
property in windows or through the WorkerGlobalScope.caches
property in workers.
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);
}
}),
),
),
);
});
Specifications
Specification |
---|
Service Workers # cache-storage-keys |
Browser compatibility
BCD tables only load in the browser