Javascript date format dd/mm/yy NOT dd/mm/yyyy - do I need to import a library?

Part 1 JS:

//Call the StoryLine player
var player=GetPlayer();

//Get today's date from the computer
var today = new Date();

//Isolate the day, the month and the year from the date
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yy = today.getFullYear().toString().substr(-2);

//combine the date elements as mm/dd/yy
//start by creating a leading zero for single digit days and months
if(dd<10) {
dd='0'+dd
}

if(mm<10) {
mm='0'+mm
}

today = mm+'/'+dd+'/'+yy;

//Send to StoryLine variable
player.SetVar("Today's_Date",today);