navigator.serviceWorker.ready.then(function(swRegistration) {
  return swRegistration.sync.register('myFirstSync');
});

self.addEventListener('sync', function(event) {
  if (event.tag == 'myFirstSync') {
    event.waitUntil(doSomeStuff());
  }
});

self.addEventListener('activate', e => {
  e.waitUntil(self.registration.navigationPreload.enable());
});

addEventListener('fetch', event => {
  event.respondWith(async function() {
    // Respond from the cache if we can
    const cachedResponse = await caches.match(event.request);
    if (cachedResponse) return cachedResponse;

    // Else, use the preloaded response, if it's there
    const response = await event.preloadResponse;
    if (response) return response;

    // Else try the network.
    return fetch(event.request);
  }());
});

navigator.serviceWorker.ready.then(function(registration) {
  registration.periodicSync.register({
    tag: 'get-latest-news',         // default: ''
    minPeriod: 12 * 60 * 60 * 1000, // default: 0
    powerState: 'avoid-draining',   // default: 'auto'
    networkState: 'avoid-cellular'  // default: 'online'
  }).then(function(periodicSyncReg) {
    // success
  }, function() {
    // failure
  })
});

self.addEventListener('periodicsync', function(event) {
  if (event.registration.tag == 'get-latest-news') {
    event.waitUntil(fetchAndCacheLatestNews());
  }
  else {
    // unknown sync, may be old, best to unregister
    event.registration.unregister();
  }
});

// You can't do this!
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('service-worker.js');
}

Link: </service-worker.js>; rel="serviceworker"; scope="/"

self.addEventListener('install', function(e) {
  e.registerForeignFetch({scopes: ['/myscope'], origins: ['*']});
});

self.addEventListener('foreignfetch', function(e) {
  // Do whatever local work is necessary to handle the fetch,
  // or just pass it through to the network:
  e.respondWith(fetch(e.request).then(response => ({
    response: response,
    origin: e.origin,
    headers: ['...']
  }));
});