var dates = ['Mon Nov 14 05:58:24 GMT+08:00 2016', 'Thu Nov 17 07:46:01 GMT+08:00 2016',
               'Tue Sep 27 07:00:06 GMT+08:00 2016', 'Wed Sep 07 10:46:50 GMT+08:00 2016',
               'Sun Jul 31 18:47:16 GMT+08:00 2016', 'Sat Jul 09 06:14:15 GMT+08:00 2016',
               'Sun Apr 24 20:33:50 GMT+08:00 2016', 'Sun Apr 03 11:48:40 GMT+08:00 2016',
               'Thu Mar 31 12:55:39 GMT+08:00 2016', 'Wed Mar 23 06:59:00 GMT+08:00 2016'];

var max = dates.reduce(function(a, b) {
  return new Date(a).getTime() > new Date(b).getTime() ? a : b;
});
// max should contain the latest date as a string.
Logger.log(max);
// Thu Nov 17 07:46:01 GMT+08:00 2016