text: var cacheName = 'hello-pwa';
  var filesToCache = [
    '.',
    'index.html',
    'css/style.css',
    'app1.js',
    'manifest.json',
    'js/main.js'
  ];
  
  /* Start the service worker and cache all of the app's content */
  self.addEventListener('install', function(e) {
    e.waitUntil(
      caches.open(cacheName).then(function(cache) {
        return cache.addAll(filesToCache);
      })
    );
  });
  
  /* Serve cached content when offline */
  self.addEventListener('fetch', function(e) {
    e.respondWith(
      caches.match(e.request).then(function(response) {
        return response || fetch(e.request);
      })
    );
  });
  