sw.js

const staticCache = "app-shell-v1";

const assetsToCache = [
  'https://cdnjs.cloudflare.com/ajax/libs/material-design-lite/1.3.0/material.indigo-pink.min.css',
  'https://fonts.gstatic.com/s/materialicons/v55/flUhRq6tzZclQEJ-Vdg-IuiaDsNcIhQ8tQ.woff2',
  'https://fonts.gstatic.com/s/roboto/v20/KFOmCnqEu92Fr1Mu4mxKKTU1Kg.woff2',
  'https://fonts.googleapis.com/css?family=Roboto:400,700',
  'https://fonts.googleapis.com/icon?family=Material+Icons',
  'assets/images/pwa-logo.png',
  'assets/js/material.min.js',
  'assets/style.css',
  'app.js',
  'favicon.ico',
  'index.html',
  '/'
];

async function cacheStaticAssets() {
  const cache = await caches.open(staticCache);
  return cache.addAll(assetsToCache);
}

async function networkFirst(request) {
  try {
    return await fetch(request);
  } catch (error) {
    console.log("[Service Worker] network error", error);
    const cache = await caches.open(staticCache);
    return cache.match(request);
  }
}

self.addEventListener("install", (event) => {
  console.log("[Service Worker] Installing service worker");
  event.waitUntil(cacheStaticAssets());
  self.skipWaiting();
});

self.addEventListener("activate", () => {
  console.log("[Service Worker] Activating service worker!");
  return self.clients.claim();
});

self.addEventListener("fetch", (event) => {
  console.log("[Service Worker] Fetch event worker!", event.request.url);
  event.respondWith(networkFirst(event.request));
});