1  const cacheName = "meloniemacreturn-v6";
  2  const coreAssets = [
  3  
  4  "/return/",
  5  "/return/index.html",
  6  "/return/manifest.json",
  7    
  8  "/return/android-chrome-192x192.png",
  9  "/return/android-chrome-512x512.png",
 10  "/return/apple-touch-icon-57x57-precomposed.png",
 11  "/return/apple-touch-icon-57x57.png",
 12  "/return/apple-touch-icon-60x60-precomposed.png",
 13  "/return/apple-touch-icon-60x60.png",
 14  "/return/apple-touch-icon-72x72-precomposed.png",
 15  "/return/apple-touch-icon-72x72.png",
 16  "/return/apple-touch-icon-76x76-precomposed.png",
 17  "/return/apple-touch-icon-76x76.png",
 18  "/return/apple-touch-icon-114x114-precomposed.png",
 19  "/return/apple-touch-icon-114x114.png",
 20  "/return/apple-touch-icon-120x120-precomposed.png",
 21  "/return/apple-touch-icon-120x120.png",
 22  "/return/apple-touch-icon-144x144-precomposed.png",
 23  "/return/apple-touch-icon-144x144.png",
 24  "/return/apple-touch-icon-152x152-precomposed.png",
 25  "/return/apple-touch-icon-152x152.png",
 26  "/return/apple-touch-icon-180x180-precomposed.png",
 27  "/return/apple-touch-icon-180x180.png",
 28  "/return/apple-touch-icon-precomposed.png",
 29  "/return/apple-touch-icon.png",
 30  "/return/browserconfig.xml",
 31  "/return/favicon-16x16.png",
 32  "/return/favicon-32x32.png",
 33  "/return/favicon.ico",
 34  "/return/icon.png",
 35  "/return/icon.svg",
 36  "/return/mstile-150x150.png",
 37  "/return/safari-pinned-tab.svg",
 38  
 39  "/return/jorge-fernandez-salas-bUz7tSY7kQs-unsplash.jpg"
 40  ];
 41  
 42  
 43  // On install, cache core assets
 44  self.addEventListener('install', function (event) {
 45  
 46    // Cache core assets
 47    event.waitUntil(caches.open(cacheName).then(function (cache) {
 48      for (let asset of coreAssets) {
 49        cache.add(new Request(asset));
 50      }
 51      return cache;
 52    }));
 53  
 54  });
 55  
 56  // Listen for request events
 57  self.addEventListener('fetch', function (event) {
 58  
 59    // Get the request
 60    let request = event.request;
 61  
 62    // Bug fix
 63    // https://stackoverflow.com/a/49719964
 64    if (event.request.cache === 'only-if-cached' && event.request.mode !== 'same-origin') return;
 65  
 66    // HTML files
 67    // Network-first
 68    if (request.headers.get('Accept').includes('text/html')) {
 69      event.respondWith(
 70        fetch(request).then(function (response) {
 71  
 72          // Create a copy of the response and save it to the cache
 73          let copy = response.clone();
 74          event.waitUntil(caches.open(cacheName).then(function (cache) {
 75            return cache.put(request, copy);
 76          }));
 77  
 78          // Return the response
 79          return response;
 80  
 81        }).catch(function (error) {
 82  
 83          // If there's no item in cache, respond with a fallback
 84          return caches.match(request).then(function (response) {
 85            return response || caches.match('/index.html');
 86          });
 87  
 88        })
 89      );
 90    }
 91  
 92    // CSS & JavaScript
 93    // Offline-first
 94    if (request.headers.get('Accept').includes('text/css') || request.headers.get('Accept').includes('text/javascript')) {
 95      event.respondWith(
 96        caches.match(request).then(function (response) {
 97          return response || fetch(request).then(function (response) {
 98  
 99            // Return the response
100            return response;
101  
102          });
103        })
104      );
105      return;
106    }
107  
108    // Images
109    // Offline-first
110    if (request.headers.get('Accept').includes('image')) {
111      event.respondWith(
112        caches.match(request).then(function (response) {
113          return response || fetch(request).then(function (response) {
114  
115            // Save a copy of it in cache
116            let copy = response.clone();
117            event.waitUntil(caches.open(cacheName).then(function (cache) {
118              return cache.put(request, copy);
119            }));
120  
121            // Return the response
122            return response;
123  
124          });
125        })
126      );
127    }
128  
129  });