https://app.findthewhy.org/serviceworker

1(function () {
2    'use strict';
3
4    // Update 'version' if you need to refresh the cache
5    var version = 'v1.0::CacheFirstSafe';
6    var offlineUrl = "/offline.html";
7
8    // Store core files in a cache (including a page to display when offline)
9    function updateStaticCache() {
10        return caches.open(version)
11            .then(function (cache) {
12                return cache.addAll([
13                    offlineUrl,
14                    
15                ]);
16            });
17    }
18
19    function addToCache(request, response) {
20        if (!response.ok && response.type !== 'opaque')
21            return;
22
23        var copy = response.clone();
24        caches.open(version)
25            .then(function (cache) {
26                cache.put(request, copy);
27            });
28    }
29
30    function serveOfflineImage(request) {
31        if (request.headers.get('Accept').indexOf('image') !== -1) {
32            return new Response('<svg role="img" aria-labelledby="offline-title" viewBox="0 0 400 300" xmlns="http://www.w3.org/2000/svg"><title id="offline-title">Offline</title><g fill="none" fill-rule="evenodd"><path fill="#D8D8D8" d="M0 0h400v300H0z"/><text fill="#9B9B9B" font-family="Helvetica Neue,Arial,Helvetica,sans-serif" font-size="72" font-weight="bold"><tspan x="93" y="172">offline</tspan></text></g></svg>', { headers: { 'Content-Type': 'image/svg+xml' } });
33        }
34    }
35
36    self.addEventListener('install', function (event) {
37        event.waitUntil(updateStaticCache());
38    });
39
40    self.addEventListener('activate', function (event) {
41        event.waitUntil(
42            caches.keys()
43                .then(function (keys) {
44                    // Remove caches whose name is no longer valid
45                    return Promise.all(keys
46                        .filter(function (key) {
47                            return key.indexOf(version) !== 0;
48                        })
49                        .map(function (key) {
50                            return caches.delete(key);
51                        })
52                    );
53                })
54        );
55    });
56
57    self.addEventListener('fetch', function (event) {
58        var request = event.request;
59
60        // Always fetch non-GET requests from the network
61        if (request.method !== 'GET' || request.url.match(/\/browserLink/ig)) {
62            event.respondWith(
63                fetch(request)
64                    .catch(function () {
65                        return caches.match(offlineUrl);
66                    })
67            );
68            return;
69        }
70
71        // For HTML requests, try the network first, fall back to the cache, finally the offline page
72        if (request.headers.get('Accept').indexOf('text/html') !== -1) {
73            event.respondWith(
74                fetch(request)
75                    .then(function (response) {
76                        // Stash a copy of this page in the cache
77                        addToCache(request, response);
78                        return response;
79                    })
80                    .catch(function () {
81                        return caches.match(request)
82                            .then(function (response) {
83                                return response || caches.match(offlineUrl);
84                            });
85                    })
86            );
87            return;
88        }
89
90        // cache first for fingerprinted resources
91        if (request.url.match(/(\?|&)v=/ig)) {
92            event.respondWith(
93                caches.match(request)
94                    .then(function (response) {
95                        return response || fetch(request)
96                            .then(function (response) {
97                                addToCache(request, response);
98                                return response || serveOfflineImage(request);
99                            })
100                            .catch(function () {
101                                return serveOfflineImage(request);
102                            });
103                    })
104            );
105
106            return;
107        }
108
109        // network first for non-fingerprinted resources
110        event.respondWith(
111            fetch(request)
112                .then(function (response) {
113                    // Stash a copy of this page in the cache
114                    addToCache(request, response);
115                    return response;
116                })
117                .catch(function () {
118                    return caches.match(request)
119                        .then(function (response) {
120                            return response || serveOfflineImage(request);
121                        })
122                        .catch(function () {
123                            return serveOfflineImage(request);
124                        });
125                })
126        );
127    });
128
129})();