File: examples/react/src/serviceWorker.js

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File: examples/react/src/serviceWorker.js
Role: Example script
Content type: text/plain
Description: Example script
Class: Countly Web SDK
Track site accesses and errors the Countly API
Author: By
Last change:
Date: 9 months ago
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// This optional code is used to register a service worker. // register() is not called by default. // This lets the app load faster on subsequent visits in production, and gives // it offline capabilities. However, it also means that developers (and users) // will only see deployed updates on subsequent visits to a page, after all the // existing tabs open on the page have been closed, since previously cached // resources are updated in the background. // To learn more about the benefits of this model and instructions on how to // opt-in, read https://bit.ly/CRA-PWA const isLocalhost = Boolean( window.location.hostname === 'localhost' || // [::1] is the IPv6 localhost address. window.location.hostname === '[::1]' || // 127.0.0.0/8 are considered localhost for IPv4. window.location.hostname.match( /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/ ) ); export function register(config) { if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) { // The URL constructor is available in all browsers that support SW. const publicUrl = new URL(process.env.PUBLIC_URL, window.location.href); if (publicUrl.origin !== window.location.origin) { // Our service worker won't work if PUBLIC_URL is on a different origin // from what our page is served on. This might happen if a CDN is used to // serve assets; see https://github.com/facebook/create-react-app/issues/2374 return; } window.addEventListener('load', () => { const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`; if (isLocalhost) { // This is running on localhost. Let's check if a service worker still exists or not. checkValidServiceWorker(swUrl, config); // Add some additional logging to localhost, pointing developers to the // service worker/PWA documentation. navigator.serviceWorker.ready.then(() => { console.log( 'This web app is being served cache-first by a service ' + 'worker. To learn more, visit https://bit.ly/CRA-PWA' ); }); } else { // Is not localhost. Just register service worker registerValidSW(swUrl, config); } }); } } function registerValidSW(swUrl, config) { navigator.serviceWorker .register(swUrl) .then(registration => { registration.onupdatefound = () => { const installingWorker = registration.installing; if (installingWorker == null) { return; } installingWorker.onstatechange = () => { if (installingWorker.state === 'installed') { if (navigator.serviceWorker.controller) { // At this point, the updated precached content has been fetched, // but the previous service worker will still serve the older // content until all client tabs are closed. console.log( 'New content is available and will be used when all ' + 'tabs for this page are closed. See https://bit.ly/CRA-PWA.' ); // Execute callback if (config && config.onUpdate) { config.onUpdate(registration); } } else { // At this point, everything has been precached. // It's the perfect time to display a // "Content is cached for offline use." message. console.log('Content is cached for offline use.'); // Execute callback if (config && config.onSuccess) { config.onSuccess(registration); } } } }; }; }) .catch(error => { console.error('Error during service worker registration:', error); }); } function checkValidServiceWorker(swUrl, config) { // Check if the service worker can be found. If it can't reload the page. fetch(swUrl, { headers: { 'Service-Worker': 'script' }, }) .then(response => { // Ensure service worker exists, and that we really are getting a JS file. const contentType = response.headers.get('content-type'); if ( response.status === 404 || (contentType != null && contentType.indexOf('javascript') === -1) ) { // No service worker found. Probably a different app. Reload the page. navigator.serviceWorker.ready.then(registration => { registration.unregister().then(() => { window.location.reload(); }); }); } else { // Service worker found. Proceed as normal. registerValidSW(swUrl, config); } }) .catch(() => { console.log( 'No internet connection found. App is running in offline mode.' ); }); } export function unregister() { if ('serviceWorker' in navigator) { navigator.serviceWorker.ready .then(registration => { registration.unregister(); }) .catch(error => { console.error(error.message); }); } }