1self.addEventListener('activate', (event) => {
2  event.waitUntil(async function() {
3    const cacheNames = await caches.keys();
4    await Promise.all(
5      cacheNames.filter((cacheName) => {
6        // Return true if you want to remove this cache,
7        // but remember that caches are shared across
8        // the whole origin
9      }).map(cacheName => caches.delete(cacheName))
10    );
11  }());
12});