https://kartra.com/sw.js

1/**
2Import the Workbox library from the Google CDN.
3It is possible to serve this locally should we want to remove the dependency on Google
4See here for more info: https://developers.google.com/web/tools/workbox/modules/workbox-sw
5**/
6importScripts('https://storage.googleapis.com/workbox-cdn/releases/3.3.1/workbox-sw.js');
7const offlinePage = '/offline/';
8// SETTINGS
9workbox.setConfig({
10  // set the local path is not using Google CDN
11  //modulePathPrefix: '/directory/to/workbox/'
12
13  // By default, workbox-sw will use the debug build for sites on localhost,
14  // but for any other origin it’ll use the production build. Force by setting to true.
15  // debug: true
16});
17
18/**
19 * Pages to cache (networkFirst)
20 */
21
22/**
23 * Add on install
24 */
25self.addEventListener('install', (event) => {
26  const urls = ['/offline/'];
27  const cacheName = workbox.core.cacheNames.runtime;
28  event.waitUntil(caches.open(cacheName).then((cache) => cache.addAll(urls)))
29});
30
31var networkFirst = workbox.strategies.networkFirst({
32  cacheName: 'cache-pages' 
33});
34
35const customHandler = async (args) => {
36  try {
37    const response = await networkFirst.handle(args);
38    return response || await caches.match(offlinePage);
39  } catch (error) {
40    return await caches.match(offlinePage);
41  }
42};
43
44workbox.routing.registerRoute(
45    new RegExp('/'), 
46    customHandler
47);
48
49// If any precache rules are defined in the Workbox setup this is where they will be injected
50workbox.precaching.precacheAndRoute([]);
51
52// skip the 'worker in waiting' phase and activate immediately
53workbox.skipWaiting();
54// claim any clients that match the worker scope immediately. requests on these pages will
55// now go via the service worker. 
56workbox.clientsClaim();