https://www.jornalmetropolis.com.br/pwabuilder-sw.js

1const OFFLINE_VERSION = 1;
2const CACHE_NAME = 'offline';
3// Customize this with a different URL if needed.
4const OFFLINE_URL = '/';
5
6self.addEventListener('install', (event) => {
7  event.waitUntil((async () => {
8    const cache = await caches.open(CACHE_NAME);
9    // Setting {cache: 'reload'} in the new request will ensure that the response
10    // isn't fulfilled from the HTTP cache; i.e., it will be from the network.
11    await cache.add(new Request(OFFLINE_URL, {cache: 'reload'}));
12  })());
13});
14
15self.addEventListener('activate', (event) => {
16  event.waitUntil((async () => {
17    // Enable navigation preload if it's supported.
18    // See https://developers.google.com/web/updates/2017/02/navigation-preload
19    if ('navigationPreload' in self.registration) {
20      await self.registration.navigationPreload.enable();
21    }
22  })());
23
24  // Tell the active service worker to take control of the page immediately.
25  self.clients.claim();
26});
27
28self.addEventListener('fetch', (event) => {
29  // We only want to call event.respondWith() if this is a navigation request
30  // for an HTML page.
31  if (event.request.mode === 'navigate') {
32    event.respondWith((async () => {
33      try {
34        // First, try to use the navigation preload response if it's supported.
35        const preloadResponse = await event.preloadResponse;
36        if (preloadResponse) {
37          return preloadResponse;
38        }
39
40        const networkResponse = await fetch(event.request);
41        return networkResponse;
42      } catch (error) {
43        // catch is only triggered if an exception is thrown, which is likely
44        // due to a network error.
45        // If fetch() returns a valid HTTP response with a response code in
46        // the 4xx or 5xx range, the catch() will NOT be called.
47        console.log('Fetch failed; returning offline page instead.', error);
48
49        const cache = await caches.open(CACHE_NAME);
50        const cachedResponse = await cache.match(OFFLINE_URL);
51        return cachedResponse;
52      }
53    })());
54  }
55
56  // If our if() condition is false, then this fetch handler won't intercept the
57  // request. If there are any other fetch handlers registered, they will get a
58  // chance to call event.respondWith(). If no fetch handlers call
59  // event.respondWith(), the request will be handled by the browser as if there
60  // were no service worker involvement.
61});