1 | // tslint:disable:no-console
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2 | // In production, we register a service worker to serve assets from local cache.
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3 |
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4 | // This lets the app load faster on subsequent visits in production, and gives
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5 | // it offline capabilities. However, it also means that developers (and users)
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6 | // will only see deployed updates on the 'N+1' visit to a page, since previously
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7 | // cached resources are updated in the background.
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8 |
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9 | // To learn more about the benefits of this model, read https://goo.gl/KwvDNy.
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10 | // This link also includes instructions on opting out of this behavior.
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11 |
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12 | const isLocalhost = Boolean(
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13 | window.location.hostname === 'localhost' ||
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14 | // [::1] is the IPv6 localhost address.
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15 | window.location.hostname === '[::1]' ||
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16 | // 127.0.0.1/8 is considered localhost for IPv4.
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17 | window.location.hostname.match(
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18 | /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
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19 | )
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20 | );
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21 |
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22 | export default function register() {
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23 | if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
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24 | // The URL constructor is available in all browsers that support SW.
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25 | const publicUrl = new URL(
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26 | process.env.PUBLIC_URL!,
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27 | window.location.toString()
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28 | );
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29 | if (publicUrl.origin !== window.location.origin) {
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30 | // Our service worker won't work if PUBLIC_URL is on a different origin
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31 | // from what our page is served on. This might happen if a CDN is used to
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32 | // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374
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33 | return;
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34 | }
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35 |
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36 | window.addEventListener('load', () => {
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37 | const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;
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38 |
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39 | if (!isLocalhost) {
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40 | // Is not local host. Just register service worker
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41 | registerValidSW(swUrl);
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42 | } else {
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43 | // This is running on localhost. Lets check if a service worker still exists or not.
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44 | checkValidServiceWorker(swUrl);
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45 | }
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46 | });
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47 | }
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48 | }
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49 |
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50 | function registerValidSW(swUrl: string) {
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51 | navigator.serviceWorker
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52 | .register(swUrl)
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53 | .then(registration => {
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54 | registration.onupdatefound = () => {
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55 | const installingWorker = registration.installing;
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56 | if (installingWorker) {
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57 | installingWorker.onstatechange = () => {
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58 | if (installingWorker.state === 'installed') {
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59 | if (navigator.serviceWorker.controller) {
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60 | // At this point, the old content will have been purged and
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61 | // the fresh content will have been added to the cache.
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62 | // It's the perfect time to display a 'New content is
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63 | // available; please refresh.' message in your web app.
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64 | console.log('New content is available; please refresh.');
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65 | } else {
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66 | // At this point, everything has been precached.
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67 | // It's the perfect time to display a
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68 | // 'Content is cached for offline use.' message.
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69 | console.log('Content is cached for offline use.');
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70 | }
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71 | }
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72 | };
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73 | }
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74 | };
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75 | })
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76 | .catch(error => {
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77 | console.error('Error during service worker registration:', error);
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78 | });
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79 | }
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80 |
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81 | function checkValidServiceWorker(swUrl: string) {
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82 | // Check if the service worker can be found. If it can't reload the page.
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83 | fetch(swUrl)
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84 | .then(response => {
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85 | // Ensure service worker exists, and that we really are getting a JS file.
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86 | if (
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87 | response.status === 404 ||
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88 | response.headers.get('content-type')!.indexOf('javascript') === -1
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89 | ) {
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90 | // No service worker found. Probably a different app. Reload the page.
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91 | navigator.serviceWorker.ready.then(registration => {
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92 | registration.unregister().then(() => {
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93 | window.location.reload();
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94 | });
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95 | });
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96 | } else {
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97 | // Service worker found. Proceed as normal.
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98 | registerValidSW(swUrl);
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99 | }
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100 | })
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101 | .catch(() => {
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102 | console.log(
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103 | 'No internet connection found. App is running in offline mode.'
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104 | );
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105 | });
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106 | }
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107 |
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108 | export function unregister() {
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109 | if ('serviceWorker' in navigator) {
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110 | navigator.serviceWorker.ready.then(registration => {
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111 | registration.unregister();
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112 | });
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113 | }
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114 | }
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