Getting System Date Time in Java Script

function getCurrentDateTime() {
var currentDate = new Date();

var dd = currentDate.getDate();
 var mm = currentDate.getMonth()+1; //January is 0!

var hh  = currentDate.getHours();
var min = currentDate.getMinutes();
var ss  = currentDate.getSeconds();

    if(dd<10){
        dd='0'+dd;
    }
    if(mm<10){
        mm='0'+mm;
    }
if(hh<10){
        hh='0'+hh;
    }
if(min<10){
        min='0'+min;
    }
    if(ss<10){
        ss='0'+ss;
    }

var datetime = currentDate.getFullYear() + "-" + mm + "-" + dd + " "+ hh + ":" + min + ":" + ss;

return datetime;
}