date.js

(function(global) {
  global.DateTime = DateTime = {};
  DateTime.instance = (function() {
    return {
      getTime: function(date, gmt_offset) {
        var date = DateTime.instance.getDate(date, gmt_offset);
        return date.getHours() + ":" + date.getMinutes();
      },

      getDate: function(date, gmt_offset) {
        var offset = -((new Date().getTimezoneOffset()) * 60 + gmt_offset);
        return new Date(date.getTime() - offset * 1000);
      }
    };
  })();
})(window);