age calculation in breezingform

Question

I use Breezingforms(joomla extensions) I have two field. 1- birthdate(persian calendar-jalali) 2-calculated_age -> textfield readonly for show Differs date. this my code:

 function showage(){
    var one_year=1000*60*60*24*365;
    var date1 = new Date();

    var  dob= ff_getElementByName('birthdate').value;
    var tmp=ff_getElementByName('birthdate').value.split("/");
    var date2=new Date(tmp[2],tmp[1]-1,tmp[0]);

    var pattern = /[0-3][0-9]\/(0|1)[0-9]\/(19|20)[0-9]{2}/; //Regex to validate date format (dd/mm/yyyy)
    if (pattern.test(dob)) {
        var y1 = date1.getTime(); //getting current year
        var y2 = date2.getTime(); //getting dob year
        var diff=Math.floor((y1-y2)/one_year);

        ff_getElementByName('calculated_age').value=diff;

    }
}

I have a problem.I use var date1 = new Date(); for get current date.but this var output not Jalali date(persian date) how solve it?