This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The CacheStorage
interface represents the storage for Cache
objects.
The interface:
- provides a master directory of all the named caches that can be accessed by a
ServiceWorker
or other type of worker orwindow
scope (you’re not limited to only using it with service workers, even though the Service Workers spec defines it) - maintains a mapping of string names to corresponding
Cache
objects
Use CacheStorage.open()
to obtain a Cache
instance.
Use CacheStorage.match()
to check if a given Request
is a key in any of the Cache
objects that the CacheStorage
object tracks.
You can access CacheStorage
through the global caches
property.
SecurityError
on untrusted origins (i.e. those that aren't using HTTPS, although this definition will likely become more complex in the future.) When testing, you can get around this by checking the "Enable Service Workers over HTTP (when toolbox is open)" option in the Firefox Devtools options/gear menu.CacheStorage.match()
is a convenience method. Equivalent functionality to match a cache entry can be implemented by opening your cache with CacheStorage.open()
, returning the entries it contains with CacheStorage.keys()
, and matching the one you want with CacheStorage.match()
.Methods
CacheStorage.match()
- Checks if a given
Request
is a key in any of theCache
objects that theCacheStorage
object tracks, and returns aPromise
that resolves to that match. CacheStorage.has()
- Returns a
Promise
that resolves totrue
if aCache
object matching thecacheName
exists. CacheStorage.open()
- Returns a
Promise
that resolves to theCache
object matching thecacheName
(a new cache is created if it doesn't already exist.) CacheStorage.delete()
- Finds the
Cache
object matching thecacheName
, and if found, deletes theCache
object and returns aPromise
that resolves totrue
. If noCache
object is found, it returnsfalse
. CacheStorage.keys()
- Returns a
Promise
that will resolve with an array containing strings corresponding to all of the namedCache
objects tracked by theCacheStorage
. Use this method to iterate over a list of all theCache
objects.
Examples
This code snippet is from the MDN sw-test example (see sw-test running live.) This service worker script waits for an InstallEvent
to fire, then runs waitUntil
to handle the install process for the app. This consists of calling CacheStorage.open
to create a new cache, then using Cache.addAll
to add a series of assets to it.
In the second code block, we wait for a FetchEvent
to fire. We construct a custom response like so:
- Check whether a match for the request is found in the CacheStorage. If so, serve that.
- If not, fetch the request from the network, then also open the cache created in the first block and add a clone of the request to it using
Cache.put
(cache.put(event.request, response.clone())
.) - If this fails (e.g. because the network is down), return a fallback response.
Finally, return whatever the custom response ended up being equal to, using FetchEvent.respondWith
.
this.addEventListener('install', function(event) { event.waitUntil( caches.open('v1').then(function(cache) { return cache.addAll([ '/sw-test/', '/sw-test/index.html', '/sw-test/style.css', '/sw-test/app.js', '/sw-test/image-list.js', '/sw-test/star-wars-logo.jpg', '/sw-test/gallery/bountyHunters.jpg', '/sw-test/gallery/myLittleVader.jpg', '/sw-test/gallery/snowTroopers.jpg' ]); }) ); }); this.addEventListener('fetch', function(event) { var response; event.respondWith(caches.match(event.request).catch(function() { return fetch(event.request); }).then(function(r) { response = r; caches.open('v1').then(function(cache) { cache.put(event.request, response); }); return response.clone(); }).catch(function() { return caches.match('/sw-test/gallery/myLittleVader.jpg'); })); });
Specifications
Specification | Status | Comment |
---|---|---|
Service Workers The definition of 'CacheStorage' in that specification. |
Editor's Draft | Initial definition. |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 40.0 | (Yes) | 44 (44)[1] | No support | ? | No support |
Accessible from Window |
43.0 | (Yes) | 44 (44)[1] | ? | ? | ? |
Accessible from WorkerGlobalScope |
43.0 | ? | 44 (44)[1] | ? | ? | ? |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | No support | No support | 44.0 (44) | (Yes) | (Yes) | (Yes) | 40.0 |
Accessible from Window |
No support | No support | 44.0 (44) | ? | ? | ? | 43.0 |
Accessible from WorkerGlobalScope |
No support | No support | 44.0 (44) | ? | ? | ? | 43.0 |
[1] Service workers (and Push) have been disabled in the Firefox 45 & 52 Extended Support Releases (ESR.)