30 | );
31 | }
32 | }
33 |
34 | export default App;
35 |
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/public/index.html:
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22 | React App
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/src/logo.svg:
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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 http://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 | // 127.0.0.1/8 is considered localhost for IPv4.
18 | window.location.hostname.match(
19 | /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
20 | )
21 | );
22 |
23 | export function register(config) {
24 | if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
25 | // The URL constructor is available in all browsers that support SW.
26 | const publicUrl = new URL(process.env.PUBLIC_URL, window.location);
27 | if (publicUrl.origin !== window.location.origin) {
28 | // Our service worker won't work if PUBLIC_URL is on a different origin
29 | // from what our page is served on. This might happen if a CDN is used to
30 | // serve assets; see https://github.com/facebook/create-react-app/issues/2374
31 | return;
32 | }
33 |
34 | window.addEventListener('load', () => {
35 | const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;
36 |
37 | if (isLocalhost) {
38 | // This is running on localhost. Let's check if a service worker still exists or not.
39 | checkValidServiceWorker(swUrl, config);
40 |
41 | // Add some additional logging to localhost, pointing developers to the
42 | // service worker/PWA documentation.
43 | navigator.serviceWorker.ready.then(() => {
44 | console.log(
45 | 'This web app is being served cache-first by a service ' +
46 | 'worker. To learn more, visit http://bit.ly/CRA-PWA'
47 | );
48 | });
49 | } else {
50 | // Is not localhost. Just register service worker
51 | registerValidSW(swUrl, config);
52 | }
53 | });
54 | }
55 | }
56 |
57 | function registerValidSW(swUrl, config) {
58 | navigator.serviceWorker
59 | .register(swUrl)
60 | .then(registration => {
61 | registration.onupdatefound = () => {
62 | const installingWorker = registration.installing;
63 | installingWorker.onstatechange = () => {
64 | if (installingWorker.state === 'installed') {
65 | if (navigator.serviceWorker.controller) {
66 | // At this point, the updated precached content has been fetched,
67 | // but the previous service worker will still serve the older
68 | // content until all client tabs are closed.
69 | console.log(
70 | 'New content is available and will be used when all ' +
71 | 'tabs for this page are closed. See http://bit.ly/CRA-PWA.'
72 | );
73 |
74 | // Execute callback
75 | if (config && config.onUpdate) {
76 | config.onUpdate(registration);
77 | }
78 | } else {
79 | // At this point, everything has been precached.
80 | // It's the perfect time to display a
81 | // "Content is cached for offline use." message.
82 | console.log('Content is cached for offline use.');
83 |
84 | // Execute callback
85 | if (config && config.onSuccess) {
86 | config.onSuccess(registration);
87 | }
88 | }
89 | }
90 | };
91 | };
92 | })
93 | .catch(error => {
94 | console.error('Error during service worker registration:', error);
95 | });
96 | }
97 |
98 | function checkValidServiceWorker(swUrl, config) {
99 | // Check if the service worker can be found. If it can't reload the page.
100 | fetch(swUrl)
101 | .then(response => {
102 | // Ensure service worker exists, and that we really are getting a JS file.
103 | if (
104 | response.status === 404 ||
105 | response.headers.get('content-type').indexOf('javascript') === -1
106 | ) {
107 | // No service worker found. Probably a different app. Reload the page.
108 | navigator.serviceWorker.ready.then(registration => {
109 | registration.unregister().then(() => {
110 | window.location.reload();
111 | });
112 | });
113 | } else {
114 | // Service worker found. Proceed as normal.
115 | registerValidSW(swUrl, config);
116 | }
117 | })
118 | .catch(() => {
119 | console.log(
120 | 'No internet connection found. App is running in offline mode.'
121 | );
122 | });
123 | }
124 |
125 | export function unregister() {
126 | if ('serviceWorker' in navigator) {
127 | navigator.serviceWorker.ready.then(registration => {
128 | registration.unregister();
129 | });
130 | }
131 | }
132 |
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11 |
12 |
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/src/index.css:
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1 | body {
2 | margin: 0;
3 | padding: 0;
4 | font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Oxygen",
5 | "Ubuntu", "Cantarell", "Fira Sans", "Droid Sans", "Helvetica Neue",
6 | sans-serif;
7 | -webkit-font-smoothing: antialiased;
8 | -moz-osx-font-smoothing: grayscale;
9 | }
10 |
11 | code {
12 | font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New",
13 | monospace;
14 | }
15 |
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/package.json:
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1 | {
2 | "name": "test-lazy-memo",
3 | "version": "0.1.0",
4 | "private": true,
5 | "dependencies": {
6 | "react": "^16.6.0",
7 | "react-dom": "^16.6.0",
8 | "react-scripts": "2.0.5"
9 | },
10 | "scripts": {
11 | "start": "react-scripts start",
12 | "build": "react-scripts build",
13 | "test": "react-scripts test",
14 | "eject": "react-scripts eject"
15 | },
16 | "eslintConfig": {
17 | "extends": "react-app"
18 | },
19 | "browserslist": [
20 | ">0.2%",
21 | "not dead",
22 | "not ie <= 11",
23 | "not op_mini all"
24 | ]
25 | }
26 |
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/src/App.css:
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1 | .App {
2 | text-align: center;
3 | }
4 |
5 | .App-logo {
6 | animation: App-logo-spin infinite 20s linear;
7 | height: 40vmin;
8 | }
9 |
10 | .App-header {
11 | background-color: #282c34;
12 | min-height: 100vh;
13 | display: flex;
14 | flex-direction: column;
15 | align-items: center;
16 | justify-content: center;
17 | font-size: calc(10px + 2vmin);
18 | color: white;
19 | }
20 |
21 | .App-link {
22 | color: #61dafb;
23 | }
24 |
25 | @keyframes App-logo-spin {
26 | from {
27 | transform: rotate(0deg);
28 | }
29 | to {
30 | transform: rotate(360deg);
31 | }
32 | }
33 |
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/src/index.js:
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1 | import React, { StrictMode, unstable_ConcurrentMode as ConcurrentMode } from 'react';
2 | import ReactDOM from 'react-dom';
3 | import './index.css';
4 | import App from './App';
5 | // import * as serviceWorker from './serviceWorker';
6 |
7 | ReactDOM.render(
8 |