update_sw.js

self.addEventListener('activate', event => {
  const cacheWhitelist = ['nombre-cache-v2'];

  event.waitUntil(
    caches.keys().then(cacheNames => Promise.all(
      cacheNames.map(cacheName => {
        if (cacheWhitelist.indexOf(cacheName === -1)) {
          return caches.delete(cacheName);
        }
      })
    ));
  );
});