PWA Day06 - generic fallback

sw.js

self.addEventListener('fetch', function(event) {
  event.respondWith(
    // Try the cache
    caches
      .match(event.request)
      .then(function(response) {
        // Fall back to network
        return response || fetch(event.request)
      })
      .catch(function() {
        // If both fail, show a generic fallback:
        return caches.match('/offline.html')
        // However, in reality you'd have many different
        // fallbacks, depending on URL & headers.
        // Eg, a fallback silhouette image for avatars.
      })
  )
})