service-worker.js

// CODELAB: Update cache names any time any of the cached files change.
const CACHE_NAME = 'static-cache-v1';

// CODELAB: Add list of files to cache here.
const FILES_TO_CACHE = [
  'index.html',
];

self.addEventListener('install', (evt) => {
  console.log('[ServiceWorker] Install');
  // CODELAB: Precache static resources here.
  evt.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      console.log('[ServiceWorker] Pre-caching offline page');
      return cache.addAll(FILES_TO_CACHE);
    })
);

  self.skipWaiting();
});

self.addEventListener('activate', (evt) => {
  console.log('[ServiceWorker] Activate');
  // CODELAB: Remove previous cached data from disk.
  evt.waitUntil(
      caches.keys().then((keyList) => {
        return Promise.all(keyList.map((key) => {
          if (key !== CACHE_NAME) {
            console.log('[ServiceWorker] Removing old cache', key);
            return caches.delete(key);
          }
        }));
      })
  );
  self.clients.claim();
});

self.addEventListener('fetch', (evt) => {
  console.log('[ServiceWorker] Fetch', evt.request.url);
  // CODELAB: Add fetch event handler here.
  if (evt.request.mode !== 'navigate') {
    // Not a page navigation, bail.
    return;
  }
  evt.respondWith(
      fetch(evt.request)
          .catch(() => {
            return caches.open(CACHE_NAME)
                .then((cache) => {
                  return cache.match('index.html');
                });
          })
  );
});