service_worker.js

var staticCacheName = 'mws-static-v1';
var allCaches = [
  staticCacheName,
];

var cache_urls = [
  'css/styles.css',
  'img/1.jpg',
  'img/2.jpg',
  'img/3.jpg',
  'img/4.jpg',
  'img/5.jpg',
  'img/6.jpg',
  'img/7.jpg',
  'img/8.jpg',
  'img/9.jpg',
  'img/10.jpg',
  'js/dbhelper.js',
  'js/main.js',
  'js/restaurant_info.js',
  'index.html',
  'restaurant.html',
  '/.'
];


self.addEventListener('install', function(event) {
  event.waitUntil(
    caches.open(staticCacheName).then(function(cache) {
      return cache.addAll(cache_urls);
    })
  );
});

self.addEventListener('activate', function(event) {
  event.waitUntil(
    caches.keys().then(function(cacheNames) {
      return Promise.all(
        cacheNames.filter(function(cacheName) {
          return cacheName.startsWith('mws-') &&
                 !allCaches.includes(cacheName);
        }).map(function(cacheName) {
          return caches.delete(cacheName);
        })
      );
    })
  );
});

self.addEventListener('fetch', function(event) {
  var requestUrl = new URL(event.request.url);
  event.respondWith(
    caches.match(event.request).then(function(response) {
      return response || fetch(event.request);
    })
  );
});