CacheStorage: match() method

{{APIRef("Service Workers API")}} {{SecureContext_Header}} {{AvailableInWorkers}} 

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

You can access CacheStorage through the {{domxref("Window.caches")}}  property in windows or through the {{domxref("WorkerGlobalScope.caches")}}  property in workers.

Cache objects are searched in creation order.

[!NOTE] caches.match() is a convenience method. Equivalent functionality is to call {{domxref("cache.match()")}}  on each cache (in the order returned by {{domxref("CacheStorage.keys()", "caches.keys()")}} ) until a {{domxref("Response")}}  is returned.

Syntax

match(request)
match(request, options)

Parameters

• request
  • : The {{domxref("Request")}}  you want to match. This can be a {{domxref("Request")}}  object or a URL string.
• options {{optional_inline}} 
  • : An object whose properties control how matching is done in the match operation. The available options are:
    • ignoreSearch
      • : A boolean value 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 value that, when set to true, prevents matching operations from validating the {{domxref("Request")}}  http method (normally only GET and HEAD are allowed.) It defaults to false.
    • ignoreVary
      • : A boolean value 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 {{domxref("Response")}}  object has a VARY header or not. It defaults to false.
    • cacheName
      • : A string that represents a specific cache to search within.

Return value

a {{jsxref("Promise")}}  that resolves to the matching {{domxref("Response")}} . If no matching response to the specified request is found, the promise resolves with undefined.

Examples

This example is from the MDN simple service worker example (see simple service worker running live). Here we wait for a {{domxref("FetchEvent")}}  to fire. We construct a custom response like so:

1. Check whether a match for the request is found in the {{domxref("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 {{domxref("Cache.put","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", (event) => {
  event.respondWith(
    caches.match(event.request).then((response) => {
      // caches.match() always resolves
      // but in case of success response will have value
      if (response !== undefined) {
        return response;
      }
      return fetch(event.request)
        .then((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((cache) => cache.put(event.request, responseClone));
          return response;
        })
        .catch(() => caches.match("/gallery/myLittleVader.jpg"));
    }),
  );
});

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Using Service Workers
• {{domxref("Cache")}} 
• {{domxref("Window.caches")}}  and {{domxref("WorkerGlobalScope.caches")}}