verify age

<SCRIPT LANGUAGE="JavaScript" TYPE="text/javascript">
function verifyAge(sFrm) {
    var frm = document.getElementById(sFrm);
 
    var month = frm.ageMo.options[frm.ageMo.selectedIndex].value;  
    var day = frm.ageDay.options[frm.ageDay.selectedIndex].value;  
    var year = frm.ageYear.options[frm.ageYear.selectedIndex].value;  
 
    if (month == '' || day == '' || year == '') {
        alert('Please select your birth date before proceeding');
        frm.ageMo.focus();
		return false;
    }
    else if (!/^([0-9]{4})$/.test(year) || !/^([0-9]{1,2})$/.test(month) || !/^([0-9]{1,2})$/.test(day)) {
		alert ('Please enter a valid date');
		return false;
	}
 
	var ud = new Date();
	var cd = new Date();
 
    ud.setMonth(month-1);
	ud.setDate(day);
 
	var diff = cd.getFullYear() - year;
 
	if (cd.getTime() < ud.getTime()) {
		diff -= 1;
	}
 
    if (diff < 17) {
        alert('You must be 18 years of age or older to use this site');
        return false;   
    }    
}
</script>
 
    Response.write("<form action="""&scriptName&"""method=""POST"" name=""registerFrm"" id=""registerFrm"" onSubmit=""return verifyAge('registerFrm');"">")
    Response.write("<select name=""ageMo"">")
    Response.write("<option value=""""></option>")
 
    for i = 1 to 12
        response.write "<option value="""&i&""">" &i&" - "&monthname(i,1) & "</option>"    
    next
 
    Response.write("</select>")
    Response.write(" / ")
    response.write("<select name=""ageDay"" style=""width:40px;"">")
    response.write ("<option value=""""></option>")
 
    for i = 1 to 31
        response.write "<option value="""&i&""">"&i&"</option>"    
    next
 
    response.write ("</select>")
    response.write (" / ")
    response.write ("<select name=""ageYear"" style=""width:60px;"">")
    response.write ("<option value=""""></option>")
 
    for i = year(now) to year(now)-90 step -1
        response.write "<option value="""&i&""">"&i&"</option>"    
    next
 
    response.write ("</select>")
    response.write ("</form>")