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
  
  // 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) => 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((error) => error);
  // }
  
  // export function unregister() {
  //   if ("serviceWorker" in navigator) {
  //     navigator.serviceWorker.ready
  //       .then((registration) => {
  //         registration.unregister();
  //       })
  //       .catch((error) => error.message);
  //   }
  // }
  