Selecting the date from drop down

<script type="text/javascript">
var monthtext=['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sept','Oct','Nov','Dec'];

function populatedropdown(dayfield, monthfield, yearfield){
var today=new Date()
var dayfield=document.getElementById(dayfield)
var monthfield=document.getElementById(monthfield)
var yearfield=document.getElementById(yearfield)
for (var i=0; i<31; i++)
dayfield.options[i]=new Option(i, i+1)
dayfield.options[today.getDate()]=new Option(today.getDate(), today.getDate(), true, true) //select today's day
for (var m=0; m<12; m++)
monthfield.options[m]=new Option(monthtext[m], monthtext[m])
monthfield.options[today.getMonth()]=new Option(monthtext[today.getMonth()], monthtext[today.getMonth()], true, true) //select today's month
var thisyear=today.getFullYear()
for (var y=0; y<80; y++){
yearfield.options[y]=new Option(y, y-1)
thisyear+=1
}
yearfield.options[0]=new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}
</script>

function populatedropdown(dayfield, monthfield, yearfield){
	var today=new Date()
	var dayfield=document.getElementById(dayfield)
	var monthfield=document.getElementById(monthfield)
	var yearfield=document.getElementById(yearfield)
	for (var i = 0; i < 31; i++) {
		dayfield.options[i] = new Option(i, i + 1)
	}
	dayfield.options[today.getDate()]=new Option(today.getDate(), today.getDate(), true, true) //select today's day
	for (var m = 0; m < 12; m++) {
		monthfield.options[m] = new Option(monthtext[m], monthtext[m])
	}
	monthfield.options[today.getMonth()]=new Option(monthtext[today.getMonth()], monthtext[today.getMonth()], true, true) //select today's month
	var thisyear=today.getFullYear()
	var yearindex = 0;
	var numberOfYears = 50;
	for (var y=thisyear; y>(thisyear - numberOfYears); y--) {
		yearfield.options[yearindex]=new Option(y, y);
		yearindex++;
		//thisyear+=1
	}
	yearfield.options[0]=new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}