HTML5 AppCache: SwapCache

gistfile1.js

window.applicationCache.addEventListener('updateready', function(e) {
  if (window.applicationCache.status == window.applicationCache.UPDATEREADY) {
    // Browser downloaded a new app cache.
    // Swap it in and reload the page to get the new hotness.
    window.applicationCache.swapCache();
    if (confirm('A new version of this site is available. Load it?')) {
      window.location.reload();
    }
  } else {
    // Manifest didn't changed. Nothing new to server.
  }
}, false);