[Feat]: Service worker

[billyrudi]

insert a service worker to lc to enable offline cache and add to home functions!

[billyrudi]

// 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]' || // 127.0.0.1/8 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 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) .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(); }); } }

[FalkWolsky]

Thank yu very much for the detailed description! A very good improvement!