How long does a formatted date have been achieved in javascript?

/**
*
* Returns a formatted date after how long is it now, such as September 5, 2009 14:15:23
* For example: The current time is September 5, 2009 14:15:23 timeLong=10 seconds Then return: September 5, 2009 14:15:33
*
* @param int timeLong a
* @param String formatString YYYY-MM-DD hh:mm:ss
*
*/
function getOneFormatDate(timeLong,formatString)
{
timeLong=parseInt(timeLong);
timeLong=timeLong*1000;
var myDate=new Date();
var futureDate=new Date(parseInt(())+timeLong);
var year=();
var month=();
var day=();
var hour=();
var minute=();
var second=();

if(hour<10)
{
hour="0"+hour;
}
if(minute<10)
{
minute="0"+minute;
}
if(second<10)
{
second="0"+second;
}
formatString=("YYYY",year);
formatString=("MM",month);
formatString=("DD",day);
formatString=("hh",hour);
formatString=("mm",minute);
formatString=("ss",second);
return formatString;
}