service-worker.js

const cacheName = 'listenup-v1';
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(cacheName).then((cache) => {
      return cache.addAll([
        './',
        './index.html',
        './main.css',
        './app.js',
        'icons/icon-96x96.png',
        'icons/icon-128x128.png',
        'icons/icon-152x152.png',
        'icons/icon-192x192.png',
        'icons/icon-512x512.png',
        'music/bach-cello-suite-1-prelude.mp3',
        // 'music/debussy-clair-de-lune.mp3',
        // 'music/beethoven-piano-sonata-14-moonlight.mp3',
        // 'music/beethoven-symphony-9-choral-excerpt.mp3.',
        // 'music/chopin-nocturne-2-e-flat-major.mp3',
        // 'music/debussy-prelude-to-the-afternoon-of-a-faun.mp3',
        // 'music/la-traviata-brindisi-verdi.mp3',
        // 'music/mozart-overture-to-the-marriage-of-figaro-k.mp3',
        // 'music/mozart-string-quartet-21-prussian.mp3'

      ]);
    })
  );
});

self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(existingCacheNames => {
      return Promise.all(
        existingCacheNames.map(existingCacheName => {
          if (existingCacheName !== cacheName) {
            return caches.delete(existingCacheName);
          }
        })
      );
    })
  );
});

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