check date using javascript

i've got stuck with checking date using javascript but then i found it's easy only using this code :

function isDate(dtStr){

var minYear=1900;

var currentTime = new Date()

var maxYear=currentTime.getFullYear()-13;

var strError="";

var mySplitResult = dtStr.split("/");

var day;

var month;

var year=parseInt(mySplitResult[2]);

var zeroday = mySplitResult[0].substring(0,1);

var zeromonth = mySplitResult[1].substring(0,1);

if(zeroday=="0")

{

day=parseInt(mySplitResult[0].substring(1,2));

}

else

{

day=parseInt(mySplitResult[0]);

}

if(zeromonth=="0")

{

month=parseInt(mySplitResult[1].substring(1,2));

}

else

{

month=parseInt(mySplitResult[1]);

}

var dayobj = new Date(year, month-1, day);

//strError= strError + dayobj;

if ((dayobj.getMonth()+1!=month)||(dayobj.getDate()!=day)||(dayobj.getFullYear()!=year))

{

strError= strError + "Mohon masukkan tanggal,bulan atau tahun yang valid";

}

// strError = strError + year;

//strError=zeroday + "--" + zeromonth + "--" + day+"-"+ month + "-" + year;

else if ( yearmaxYear){

strError= strError + "Maaf, usia Anda tidak memenuhi syarat min. 13 thn";

}

/**/

//return strError;

return strError ;

}

maybe u need this , just copy paste this function and run it... enjoy...