Как реализовать Offline режим в Frontend приложении

// main.js
if ('serviceWorker' in navigator) {
  navigator.serviceWorker.register('/sw.js')
    .then(registration => console.log('SW registered'))
    .catch(err => console.log('SW registration failed'));
}

const CACHE_NAME = 'my-app-cache-v1';
const urlsToCache = [
  '/',
  '/styles.css',
  '/app.js'
];

self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(cache => cache.addAll(urlsToCache))
  );
});

self.addEventListener('fetch', event => {
  event.respondWith(
    caches.match(event.request)
      .then(response => response || fetch(event.request))
  );
});