https://www.urfaekspres.com/sw.js?v=1

1/* eslint-disable compat/compat */
2
3var OFFLINE_PAGE = 'offline/index.html';
4var OFFLINE_IMG = 'offline/offline.jpg';
5
6self.addEventListener('install', function(event) {
7    event.waitUntil(
8        caches.open('offline').then(function(cache) {
9            return cache.addAll([OFFLINE_PAGE, OFFLINE_IMG]);
10        })
11    );
12});
13
14self.addEventListener('fetch', function(event) {
15    var request = event.request;
16
17    if (event.request.mode === 'navigate') {
18        event.respondWith(
19            fetch(request).catch(function() {
20                return caches.match(OFFLINE_PAGE);
21            })
22        );
23    } else if (event.request.url.includes(OFFLINE_IMG)) {
24        event.respondWith(
25            caches.match(request).then(function(response) {
26                return response || fetch(request);
27            })
28        );
29    }
30});