src/registerServiceWorker.js

   1 // In production, we register a service worker to serve assets from local cache.
   2
   3 // This lets the app load faster on subsequent visits in production, and gives
   4 // it offline capabilities. However, it also means that developers (and users)
   5 // will only see deployed updates on the "N+1" visit to a page, since previously
   6 // cached resources are updated in the background.
   7
   8 // To learn more about the benefits of this model, read https://goo.gl/KwvDNy.
   9 // This link also includes instructions on opting out of this behavior.
  10
  11 export default function register() {
  12   if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) {
  13     window.addEventListener('load', () => {
  14       const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`;
  15       navigator.serviceWorker
  16         .register(swUrl)
  17         .then(registration => {
  18           registration.onupdatefound = () => {
  19             const installingWorker = registration.installing;
  20             installingWorker.onstatechange = () => {
  21               if (installingWorker.state === 'installed') {
  22                 if (navigator.serviceWorker.controller) {
  23                   // At this point, the old content will have been purged and
  24                   // the fresh content will have been added to the cache.
  25                   // It's the perfect time to display a "New content is
  26                   // available; please refresh." message in your web app.
  27                   console.log('New content is available; please refresh.');
  28                 } else {
  29                   // At this point, everything has been precached.
  30                   // It's the perfect time to display a
  31                   // "Content is cached for offline use." message.
  32                   console.log('Content is cached for offline use.');
  33                 }
  34               }
  35             };
  36           };
  37         })
  38         .catch(error => {
  39           console.error('Error during service worker registration:', error);
  40         });
  41     });
  42   }
  43 }
  44
  45 export function unregister() {
  46   if ('serviceWorker' in navigator) {
  47     navigator.serviceWorker.ready.then(registration => {
  48       registration.unregister();
  49     });
  50   }
  51 }