BackgroundFetchRegistration

Also inherits properties from its parent, EventTarget.

BackgroundFetchRegistration.id Read only Experimental

A string containing the background fetch's ID.

BackgroundFetchRegistration.uploadTotal Read only Experimental

A number containing the total number of bytes to be uploaded.

BackgroundFetchRegistration.uploaded Read only Experimental

A number containing the size in bytes successfully sent, initially 0.哈哈哈

BackgroundFetchRegistration.downloadTotal Read only Experimental

A number containing the total size in bytes of this download. This is the value set when the background fetch was registered, or 0.

BackgroundFetchRegistration.downloaded Read only Experimental

A number containing the size in bytes that has been downloaded, initially 0.

BackgroundFetchRegistration.result Read only Experimental

Returns an empty string initially, on completion either the string "success" or "failure".

BackgroundFetchRegistration.failureReason Read only Experimental

A string with a value that indicates a reason for a background fetch failure. Can be one of the following values: "", "aborted", "bad-status", "fetch-error", "quota-exceeded", "download-total-exceeded".

BackgroundFetchRegistration.recordsAvailable Read only Experimental

A boolean indicating whether the recordsAvailable flag is set.

Also inherits methods from its parent, EventTarget.

BackgroundFetchRegistration.abort() Experimental

Aborts the background fetch. Returns a Promise that resolves with true if the fetch was successfully aborted.

BackgroundFetchRegistration.match() Experimental

Returns a single BackgroundFetchRecord object which is the first match for the arguments.

BackgroundFetchRegistration.matchAll() Experimental

Returns a Promise that resolves with an array of BackgroundFetchRecord objects containing requests and responses.

Also inherits events from its parent, EventTarget.

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface.

progress Experimental

Fired when there is a change to any of the following properties: uploaded, downloaded, result or failureReason.

The following code creates a BackGroundFetchRegistration as bgFetch, with an id of "my-fetch".

navigator.serviceWorker.ready.then(async (swReg) => {
  const bgFetch = await swReg.backgroundFetch.fetch(
    "my-fetch",
    ["/ep-5.mp3", "ep-5-artwork.jpg"],
    {
      title: "Episode 5: Interesting things.",
      icons: [
        {
          sizes: "300x300",
          src: "/ep-5-icon.png",
          type: "image/png",
        },
      ],
      downloadTotal: 60 * 1024 * 1024,
    },
  );
});

Logging the id to the console returns "my-fetch".

console.log(bgFetch.id); // "my-fetch"

The match() method can be used to find a particular BackgroundFetchRecord from those that are part of the registration.

bgFetch.match("/ep-5.mp3").then(async (record) => {
  if (!record) {
    console.log("No record found");
    return;
  }

  console.log(`Here's the request`, record.request);
  const response = await record.responseReady;
  console.log(`And here's the response`, response);
});