ServiceWorkerRegistration: свойство backgroundFetch

// main.js
async function requestBackgroundFetch(movieData) {
  const swRegistration = await navigator.serviceWorker.ready;
  const fetchRegistration = await swRegistration.backgroundFetch.fetch(
    "download-movie",
    ["/my-movie-part-1.webm", "/my-movie-part-2.webm"],
    {
      icons: movieIcons,
      title: "Downloading my movie",
      downloadTotal: 60 * 1024 * 1024,
      label: "Downloading a show",
    },
  );
  //...
}