CacheStorage

CacheStorage interface represents the storage for Cache 对象。

The interface:

使用 CacheStorage.open() to obtain a Cache 实例。

使用 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 特性。

注意 : CacheStorage always rejects with a 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.
注意 : CacheStorage.match() is a convenience method. Equivalent functionality to match a cache entry can be implemented by returning an array of cache names from CacheStorage.keys() , opening each cache with CacheStorage.open() , and matching the one you want with Cache.match() .

方法

CacheStorage.match()
Checks if a given Request is a key in any of the Cache objects that the CacheStorage object tracks, and returns a Promise that resolves to that match.
CacheStorage.has()
返回 Promise that resolves to true if a Cache object matching the cacheName exists.
CacheStorage.open()
返回 Promise that resolves to the Cache object matching the cacheName (a new cache is created if it doesn't already exist.)
CacheStorage.delete()
Finds the Cache object matching the cacheName , and if found, deletes the Cache object and returns a Promise that resolves to true . If no Cache object is found, it resolves to false .
CacheStorage.keys()
返回 Promise that will resolve with an array containing strings corresponding to all of the named Cache objects tracked by the CacheStorage . Use this method to iterate over a list of all the Cache 对象。

范例

This code snippet is from the MDN sw-test example (见 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:

  1. Check whether a match for the request is found in the CacheStorage. If so, serve that.
  2. 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()) .)
  3. 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 .

self.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'
      ]);
    })
  );
});
self.addEventListener('fetch', function(event) {
  event.respondWith(caches.match(event.request).then(function(response) {
    // caches.match() always resolves
    // but in case of success response will have value
    if (response !== undefined) {
      return response;
    } else {
      return fetch(event.request).then(function (response) {
        // response may be used only once
        // we need to save clone to put one copy in cache
        // and serve second one
        let responseClone = response.clone();
        caches.open('v1').then(function (cache) {
          cache.put(event.request, responseClone);
        });
        return response;
      }).catch(function () {
        return caches.match('/sw-test/gallery/myLittleVader.jpg');
      });
    }
  }));
});
					

This snippet shows how the API can be used outside of a service worker context, and uses the await operator for much more readable code.

// Try to get data from the cache, but fall back to fetching it live.
async function getData() {
   const cacheVersion = 1;
   const cacheName    = `myapp-${ cacheVersion }`;
   const url          = 'https://jsonplaceholder.typicode.com/todos/1';
   let cachedData     = await getCachedData( cacheName, url );
   if ( cachedData ) {
      console.log( 'Retrieved cached data' );
      return cachedData;
   }
   console.log( 'Fetching fresh data' );
   const cacheStorage = await caches.open( cacheName );
   await cacheStorage.add( url );
   cachedData = await getCachedData( cacheName, url );
   await deleteOldCaches( cacheName );
   return cachedData;
}
// Get data from the cache.
async function getCachedData( cacheName, url ) {
   const cacheStorage   = await caches.open( cacheName );
   const cachedResponse = await cacheStorage.match( url );
   if ( ! cachedResponse || ! cachedResponse.ok ) {
      return false;
   }
   return await cachedResponse.json();
}
// Delete any old caches to respect user's disk space.
async function deleteOldCaches( currentCache ) {
   const keys = await caches.keys();
   for ( const key of keys ) {
      const isOurCache = 'myapp-' === key.substr( 0, 6 );
      if ( currentCache === key || ! isOurCache ) {
         continue;
      }
      caches.delete( key );
   }
}
try {
   const data = await getData();
   console.log( { data } );
} catch ( error ) {
   console.error( { error } );
}
					

规范

规范 状态 Comment
服务工作者
The definition of 'CacheStorage' in that specification.
工作草案 初始定义。

浏览器兼容性

更新 GitHub 上的兼容性数据
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
CacheStorage
Chrome 40
40
Accessible from Window from version 43.
Accessible from WorkerGlobalScope from version 43.
Edge ≤18 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 27 Safari 11.1 WebView Android 40
40
Accessible from Window from version 43.
Accessible from WorkerGlobalScope from version 43.
Chrome Android 40
40
Accessible from Window from version 43.
Accessible from WorkerGlobalScope from version 43.
Firefox Android 44 Opera Android 27 Safari iOS 11.3 Samsung Internet Android 4.0
4.0
Accessible from Window from Samsung Internet 4.0.
Accessible from WorkerGlobalScope from Samsung Internet 4.0.
delete
Chrome 40 Edge 16 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 27 Safari 11.1 WebView Android 40 Chrome Android 40 Firefox Android 44 Opera Android 27 Safari iOS Yes Samsung Internet Android 4.0
has
Chrome 40 Edge 16 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 27 Safari 11.1 WebView Android 40 Chrome Android 40 Firefox Android 44 Opera Android 27 Safari iOS Yes Samsung Internet Android 4.0
keys
Chrome 40 Edge 16 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 27 Safari 11.1 WebView Android 40 Chrome Android 40 Firefox Android 44 Opera Android 27 Safari iOS Yes Samsung Internet Android 4.0
match
Chrome 54
54
部分支持 40
The options parameter only supports ignoreSearch ,和 cacheName .
Edge 16 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 41
41
部分支持 27
The options parameter only supports ignoreSearch ,和 cacheName .
Safari 11.1 WebView Android 54
54
部分支持 40
The options parameter only supports ignoreSearch ,和 cacheName .
Chrome Android 54
54
部分支持 40
The options parameter only supports ignoreSearch ,和 cacheName .
Firefox Android 44 Opera Android 41
41
部分支持 27
The options parameter only supports ignoreSearch ,和 cacheName .
Safari iOS Yes Samsung Internet Android 6.0
6.0
部分支持 4.0
The options parameter only supports ignoreSearch ,和 cacheName .
open
Chrome 40 Edge 16 Firefox 44
44
Extended Support Releases (ESR) before Firefox 78 ESR do not support service workers and the Push API.
IE No Opera 27 Safari 11.1 WebView Android 40 Chrome Android 40 Firefox Android 44 Opera Android 27 Safari iOS Yes Samsung Internet Android 4.0
Secure context required
Chrome 65 Edge ≤79 Firefox 44 IE No Opera 52 Safari Yes WebView Android 65 Chrome Android 65 Firefox Android 44 Opera Android 47 Safari iOS Yes Samsung Internet Android 9.0

图例

完整支持
完整支持
不支持
不支持
实验。期望将来行为有所改变。
实验。期望将来行为有所改变。
见实现注意事项。

另请参阅