64 | );
65 | }
66 |
67 | export default App;
68 |
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/public/index.html:
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27 | React App
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/src/serviceWorker.js:
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1 | // This optional code is used to register a service worker.
2 | // register() is not called by default.
3 |
4 | // This lets the app load faster on subsequent visits in production, and gives
5 | // it offline capabilities. However, it also means that developers (and users)
6 | // will only see deployed updates on subsequent visits to a page, after all the
7 | // existing tabs open on the page have been closed, since previously cached
8 | // resources are updated in the background.
9 |
10 | // To learn more about the benefits of this model and instructions on how to
11 | // opt-in, read https://bit.ly/CRA-PWA
12 |
13 | const isLocalhost = Boolean(
14 | window.location.hostname === 'localhost' ||
15 | // [::1] is the IPv6 localhost address.
16 | window.location.hostname === '[::1]' ||
17 | // 127.0.0.0/8 are considered localhost for IPv4.
18 | window.location.hostname.match(/^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/)
19 | );
20 |
21 | export function register(config) {
22 | if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
23 | // The URL constructor is available in all browsers that support SW.
24 | const publicUrl = new URL(process.env.PUBLIC_URL, window.location.href);
25 | if (publicUrl.origin !== window.location.origin) {
26 | // Our service worker won't work if PUBLIC_URL is on a different origin
27 | // from what our page is served on. This might happen if a CDN is used to
28 | // serve assets; see https://github.com/facebook/create-react-app/issues/2374
29 | return;
30 | }
31 |
32 | window.addEventListener('load', () => {
33 | const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;
34 |
35 | if (isLocalhost) {
36 | // This is running on localhost. Let's check if a service worker still exists or not.
37 | checkValidServiceWorker(swUrl, config);
38 |
39 | // Add some additional logging to localhost, pointing developers to the
40 | // service worker/PWA documentation.
41 | navigator.serviceWorker.ready.then(() => {
42 | console.log(
43 | 'This web app is being served cache-first by a service ' +
44 | 'worker. To learn more, visit https://bit.ly/CRA-PWA'
45 | );
46 | });
47 | } else {
48 | // Is not localhost. Just register service worker
49 | registerValidSW(swUrl, config);
50 | }
51 | });
52 | }
53 | }
54 |
55 | function registerValidSW(swUrl, config) {
56 | navigator.serviceWorker
57 | .register(swUrl)
58 | .then(registration => {
59 | registration.onupdatefound = () => {
60 | const installingWorker = registration.installing;
61 | if (installingWorker == null) {
62 | return;
63 | }
64 | installingWorker.onstatechange = () => {
65 | if (installingWorker.state === 'installed') {
66 | if (navigator.serviceWorker.controller) {
67 | // At this point, the updated precached content has been fetched,
68 | // but the previous service worker will still serve the older
69 | // content until all client tabs are closed.
70 | console.log(
71 | 'New content is available and will be used when all ' +
72 | 'tabs for this page are closed. See https://bit.ly/CRA-PWA.'
73 | );
74 |
75 | // Execute callback
76 | if (config && config.onUpdate) {
77 | config.onUpdate(registration);
78 | }
79 | } else {
80 | // At this point, everything has been precached.
81 | // It's the perfect time to display a
82 | // "Content is cached for offline use." message.
83 | console.log('Content is cached for offline use.');
84 |
85 | // Execute callback
86 | if (config && config.onSuccess) {
87 | config.onSuccess(registration);
88 | }
89 | }
90 | }
91 | };
92 | };
93 | })
94 | .catch(error => {
95 | console.error('Error during service worker registration:', error);
96 | });
97 | }
98 |
99 | function checkValidServiceWorker(swUrl, config) {
100 | // Check if the service worker can be found. If it can't reload the page.
101 | fetch(swUrl, {
102 | headers: { 'Service-Worker': 'script' },
103 | })
104 | .then(response => {
105 | // Ensure service worker exists, and that we really are getting a JS file.
106 | const contentType = response.headers.get('content-type');
107 | if (
108 | response.status === 404 ||
109 | (contentType != null && contentType.indexOf('javascript') === -1)
110 | ) {
111 | // No service worker found. Probably a different app. Reload the page.
112 | navigator.serviceWorker.ready.then(registration => {
113 | registration.unregister().then(() => {
114 | window.location.reload();
115 | });
116 | });
117 | } else {
118 | // Service worker found. Proceed as normal.
119 | registerValidSW(swUrl, config);
120 | }
121 | })
122 | .catch(() => {
123 | console.log('No internet connection found. App is running in offline mode.');
124 | });
125 | }
126 |
127 | export function unregister() {
128 | if ('serviceWorker' in navigator) {
129 | navigator.serviceWorker.ready
130 | .then(registration => {
131 | registration.unregister();
132 | })
133 | .catch(error => {
134 | console.error(error.message);
135 | });
136 | }
137 | }
138 |
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