js 日期、星座的级联显示

function birthdayOnchange(obj) {
var year = $("<%= DDL_Year.ClientID%>").value;

if (year == "year")
return;
else
year = parseInt(year, 10);

var month = $("<%=DDL_Month.ClientID%>").value;
if (month == "month")
return;
else
month = parseInt(month, 10);

var day = $("<%=DDL_Day.ClientID%>").value;
var wholeday = getDays(year, month);

if (1) {
var options = $("<%=DDL_Day.ClientID%>").options;
for (var i = 1; i <= wholeday; i++) {
var j = i.toString();
j = j.length == 1 ? "0" + j : j;
options.length = i + 1;
options[i].value = j;
options[i].text = j;
if (day <= wholeday && i == day) {
options[i].selected = true;
}
}
}
}

function getDays(year, month) {
var dayarr = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

if (month == 2) {
if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0 || year < 1900)
return 29;
else
return dayarr[month - 1];
}
else {
return dayarr[month - 1];
}
}

function adjustAstro() {
var v_astro = getAstro($("<%=DDL_Month.ClientID%>").value, $("<%=DDL_Day.ClientID%>").value);
$("<%=astro.ClientID %>").options[0].text = v_astro;
}

function getAstro(v_month, v_day) {
v_month = parseInt(v_month, 10)
v_day = parseInt(v_day, 10);

if ((v_month == 12 && v_day >= 22)
|| (v_month == 1 && v_day <= 20)) {
return "魔羯座";
}
else if ((v_month == 1 && v_day >= 21)
|| (v_month == 2 && v_day <= 19)) {
return "水瓶座";
}
else if ((v_month == 2 && v_day >= 20)
|| (v_month == 3 && v_day <= 20)) {
return "双鱼座";
}
else if ((v_month == 3 && v_day >= 21)
|| (v_month == 4 && v_day <= 20)) {
return "白羊座";
}
else if ((v_month == 4 && v_day >= 21)
|| (v_month == 5 && v_day <= 21)) {
return "金牛座";
}
else if ((v_month == 5 && v_day >= 22)
|| (v_month == 6 && v_day <= 21)) {
return "双子座";
}
else if ((v_month == 6 && v_day >= 22)
|| (v_month == 7 && v_day <= 22)) {
return "巨蟹座";
}
else if ((v_month == 7 && v_day >= 23)
|| (v_month == 8 && v_day <= 23)) {
return "狮子座";
}
else if ((v_month == 8 && v_day >= 24)
|| (v_month == 9 && v_day <= 23)) {
return "处女座";
}
else if ((v_month == 9 && v_day >= 24)
|| (v_month == 10 && v_day <= 23)) {
return "天秤座";
}
else if ((v_month == 10 && v_day >= 24)
|| (v_month == 11 && v_day <= 22)) {
return "天蝎座";
}
else if ((v_month == 11 && v_day >= 23)
|| (v_month == 12 && v_day <= 21)) {
return "射手座";
}
return "";
}

<DIV>出生日期：</DIV>
<DIV>
<asp:DropDownList ID="DDL_Year" runat="server"  onchange="birthdayOnchange(this);"></asp:DropDownList> 年
<asp:DropDownList ID="DDL_Month" runat="server"  onchange="birthdayOnchange(this);adjustAstro();"></asp:DropDownList> 月
<asp:DropDownList ID="DDL_Day" runat="server" onchange="adjustAstro();"></asp:DropDownList> 日
</DIV>

<DIV>星座：</DIV>
<DIV>
<SELECT id=astro disabled name=astro runat="server">
<OPTION selected>处女座</OPTION>
</SELECT>
</DIV>