Reload until application cache is in sync (noupdate). If you don't reload after app cache is updated, you'll still be using old html/css/js until the next time you reload. Should be called initially with a callback that loads your application like you normally would.

whenCacheInSync.js

function whenCacheInSync(callback) {
  // 1. Checking
  var onChecking = function () {
    window.applicationCache.removeEventListener('checking', onChecking);

    window.applicationCache.addEventListener('noupdate', onNoUpdate);
    window.applicationCache.addEventListener('downloading', onDownloading);
  };

  // 1A. No updates, load app
  var onNoUpdate = function () {
    window.applicationCache.removeEventListener('noupdate', onNoUpdate);
    window.applicationCache.removeEventListener('downloading', onDownloading);

    callback();
  };

  // 1B. Updates available, need to download...
  var onDownloading = function () {
    window.applicationCache.removeEventListener('noupdate', onNoUpdate);
    window.applicationCache.removeEventListener('downloading', onDownloading);

    window.applicationCache.addEventListener('updateready', onUpdateReady);
  };

  // 2. Updates downloaded, reload...
  var onUpdateReady = function () {
    window.location.reload();
  };

  window.applicationCache.addEventListener('checking', onChecking);
}