[Javascript] DateAdd

// 예 add_DATEs("2012-12-31", 3) 이면 2013-01-03을 리턴
function add_DATEs(dateformat, dates) {
  dateformat = clear_DateSTRING(dateformat);
  var int_millisecond = 1;
  var int_second      = 1000 * int_millisecond;
  var int_minute      = 60 * int_second;
  var int_hour        = 60 * int_minute;
  var int_day         = 24 * int_hour;
  
  var YY_form = CInt(Left(dateformat, 4));
  var MM_form = CInt(Mid(dateformat, 5, 2))-1;
  var DD_form = CInt(Right(dateformat, 2));
  
  var date = new Date(YY_form, MM_form, DD_form);
  var date_milliseconds = date.valueOf();
  var add_milliseconds  = dates * int_day;
  var ret_date = new Date(date_milliseconds + add_milliseconds);
  
  var year  = ret_date.getFullYear();
  var month = ret_date.getMonth() + 1;
  if ( month < 10 ) {
    month = "0" + month;
  }
  var day   = ret_date.getDate();
  if ( day < 10 ) {
    day = "0" + day;
  }
  
  return ( "" + year + month + day );
}