applicationCache: Overview

gistfile1.js

var appCache = window.applicationCache;

//Update when ready
appCache.onupdateready = function() {
  if(appCache.status == 'UPDATEREADY') {
    appCache.swapCache();
    if(confirm("New content available. Reload to show?")) {
      window.location.reload();
    }
  }
};

//Manual update
setInterval(function() {
  appCache.update();
  if (appCache.status == 'UPDATEREADY') {
    appCache.swapCache();  // The fetch was successful, swap in the new cache.
  }
}, 100000000);