add two time value in jquery

var s = update_total_bill_add.split(':');
    var e = spend.split(':');

        var min = parseInt(e[1])+parseInt(s[1]);
        var hour_carry = 0;
        if(min < 0){
            min += 60;
            hour_carry += 1;
        }
        var hour = parseInt(e[0])+parseInt(s[0])+parseInt(hour_carry);
        var diff = parseInt(hour) + ":" + parseInt(min);
alert(diff);