const CACHE_NAME = 'pages-converter-v1'; const urlsToCache = [ '/', '/manifest.json' ]; 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 => { if (response) { return response; } return fetch(event.request); } ) ); });