simple service worker for reveal.js

index.html

<script>
if (navigator.serviceWorker) {
  navigator.serviceWorker.register('./serviceworker.js', {
      scope: './'
  });
}
</script>

serviceworker.js

var version = 'v1::';

self.addEventListener("fetch", function(event) {
if (event.request.method !== 'GET') {
  return;
}

event.respondWith(
  caches
    .match(event.request)
    .then(function(cached) {
      var networked = fetch(event.request)
        .then(fetchedFromNetwork, unableToResolve)
        .catch(unableToResolve);

      return cached || networked;

      function fetchedFromNetwork(response) {
        var cacheCopy = response.clone();
        caches
          .open(version + 'pages')
          .then(function add(cache) {
            cache.put(event.request, cacheCopy);
          });

        return response;
      }


      function unableToResolve () {
        return new Response('<h1>Service Unavailable</h1>', {
          status: 503,
          statusText: 'Service Unavailable',
          headers: new Headers({
            'Content-Type': 'text/html'
          })
        });
      }
    })
);
});

self.addEventListener("activate", function(event) {
event.waitUntil(
  caches
    .keys()
    .then(function (keys) {
      return Promise.all(
        keys
          .filter(function (key) {
            return !key.startsWith(version);
          })
          .map(function (key) {
            return caches.delete(key);
          })
      );
    })
);
});