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FetchEvent: request property

The request read-only property of the FetchEvent interface returns the Request that triggered the event handler.

This property is non-nullable (since version 46, in the case of Firefox.) If a request is not provided by some other means, the constructor options object must contain a request (see FetchEvent().)

Value

A Request object.

Examples

This code snippet is from the service worker fetch sample (run the fetch sample live). The onfetch event handler listens for the fetch event. When fired, pass a promise that back to the controlled page to FetchEvent.respondWith(). This promise resolves to the first matching URL request in the Cache object. If no match is found, the code fetches a response from the network.

The code also handles exceptions thrown from the fetch() operation. Note that an HTTP error response (e.g., 404) will not trigger an exception. It will return a normal response object that has the appropriate error code set.

js

self.addEventListener("fetch", (event) => {
  console.log("Handling fetch event for", event.request.url);

  event.respondWith(
    caches.match(event.request).then((response) => {
      if (response) {
        console.log("Found response in cache:", response);

        return response;
      }
      console.log("No response found in cache. About to fetch from network…");

      return fetch(event.request)
        .then((response) => {
          console.log("Response from network is:", response);

          return response;
        })
        .catch((error) => {
          console.error("Fetching failed:", error);

          throw error;
        });
    }),
  );
});

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
request 40 17 44 No 27 11.1 40 40 44 27 11.3 4.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/FetchEvent/request