CacheStorage.match() - Web APIs 编辑

The match() method of the CacheStorage interface checks if a given Request or url string is a key for a stored Response. This method returns a Promise for a Response, or a Promise which resolves to undefined if no match is found.

You can access CacheStorage through the global caches property.

Cache objects are searched in creation order.

Note: caches.match() is a convenience method. Equivalent functionality is to call cache.match() on each cache (in the order returned by caches.keys()) until a Response is returned.

Syntax

caches.match(request, options).then(function(response) {
  // Do something with the response
});

Parameters

request

The Request you want to match.  This can be a  Request object or a URL string.

options Optional

An object whose properties control how matching is done in the match operation. The available options are:

• ignoreSearch: A Boolean that specifies whether the matching process should ignore the query string in the url.  For example, if set to true, the ?value=bar part of http://foo.com/?value=bar would be ignored when performing a match. It defaults to false.
• ignoreMethod: A Boolean that, when set to true, prevents matching operations from validating the Request http method (normally only GET and HEAD are allowed.) It defaults to false.
• ignoreVary: A Boolean that, when set to true, tells the matching operation not to perform VARY header matching. In other words, if the URL matches you will get a match regardless of whether the Response object has a VARY header or not. It defaults to false.
• cacheName: A DOMString that represents a specific cache to search within.

Return value

a Promise that resolves to the matching Response. If no matching response to the specified request is found, the promise resolves with undefined.

Examples

This example is from the MDN sw-test example (see sw-test running live). Here 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 using CacheStorage.match(). If so, serve that.
2. If not, open the v1 cache using open(), put the default network request in the cache using Cache.put() and return a clone of the default network request using return response.clone(). The last is necessary because put() consumes the response body.
3. If this fails (e.g., because the network is down), return a fallback response.

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');
      });
    }
  }));
});

Specifications

Specification	Status	Comment
Service Workers The definition of 'CacheStorage: match' in that specification.	Working Draft	Initial definition.

Browser compatibility

BCD tables only load in the browser

See also

• Using Service Workers
• Cache
• WindowOrWorkerGlobalScope.caches