下拉月日

var months=[1,2,3,4,5,6,7,8,9,10,11,12];
$.each(months, function(i, value){
var opts=$("<option></option>");
opts.val(value).text(value).appendTo("#BirthMonth");
});
$("<option></option>").val("").html("請選擇").appendTo("#BirthDate");


$("#BirthMonth").change(function(){
$("#BirthDate").empty();
var days=31;
var yearvalue=$.trim($("#BirthYear").val()) == "" ? new Date().getFullYear() : parseInt($("#BirthYear").val()) + 1911;
switch($(this).val()){
case "4":
case "6":
case "9":
case "11":
days=30;
break;
case "2":
days=(yearvalue%400==0 || (yearvalue%4==0 && yearvalue%100!=0)) ? 29 : 28; //29 days in bissextile February
break;
}
for(var i=1; i<=days; i++){
var opts=$("<option></option>");
opts.val(i).text(i).appendTo("#BirthDate");
}
});