text: // 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
  var 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.
          var 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', function () {
              var 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(function () {
                      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(function (registration) {
          registration.onupdatefound = function () {
              var installingWorker = registration.installing;
              if (installingWorker == null) {
                  return;
              }
              installingWorker.onstatechange = function () {
                  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(function (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(function (response) {
          // Ensure service worker exists, and that we really are getting a JS file.
          var 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(function (registration) {
                  registration.unregister().then(function () {
                      window.location.reload();
                  });
              });
          }
          else {
              // Service worker found. Proceed as normal.
              registerValidSW(swUrl, config);
          }
      })
          .catch(function () {
          console.log('No internet connection found. App is running in offline mode.');
      });
  }
  export function unregister() {
      if ('serviceWorker' in navigator) {
          navigator.serviceWorker.ready
              .then(function (registration) {
              registration.unregister();
          })
              .catch(function (error) {
              console.error(error.message);
          });
      }
  }
  