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serviceWorker.js 4.83 KiB
// 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 http://bit.ly/CRA-PWA
const isLocalhost = Boolean(
  window.location.hostname === 'localhost' ||
    // [::1] is the IPv6 localhost address.
    window.location.hostname === '[::1]' ||
    // 127.0.0.1/8 is 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 http://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 http://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) .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(); }); } }