index.js of Service Worker that Manages Cache

self.addEventListener('install', function(event) {
  var urlsToCache = [
    '/',
    'js/main.js',
    'css/main.css',
    'imgs/icon.png',
    'https://fonts.gstatic.com/s/roboto/v15/2UX7WLTfW3W8TclTUvlFyQ.woff',
    'https://fonts.gstatic.com/s/roboto/v15/d-6IYplOFocCacKzxwXSOD8E0i7KZn-EPnyo3HZu7kw.woff'
  ];
  //var cacheName = 'app-shell-cache-v1';
  var cacheName = 'wittr-static-v1';
  event.waitUntil(
    // TODO: open a cache named 'wittr-static-v1'
    // Add cache the urls from urlsToCache
    caches.open(cacheName).then(function(cache) {
      return cache.addAll(urlsToCache);
    }).then(function() {
      return self.skipWaiting();
    })
  );
});

self.addEventListener('fetch', function(event) {
  // Leave this blank for now.
  // We'll get to this in the next task.
  event.respondWith(
    caches.match(event.request)
      .then(function(response) {
        return response || fetch(event.request);
      })
  );
});