<table>
<tr>
<td width="23%" align="right"><span style="color:#F30">*</span>出生日期：</td>
<td> <select id="year" onchange="changeday()" name="year"> <option value="">年</option></select><select id="month" name="month" onchange="changeday()"><option value="">月</option> </select><select id="day" name="day" ><option value="">日</option> </select>
<script type="text/javascript" language="javascript">
var curdate = new Date();
var year = document.getElementById("year");
var month = document.getElementById("month");
var day = document.getElementById("day");
//绑定年份月分的默认
function add() {
var curyear = curdate.getFullYear();
var minyear = curyear - 80;
var maxyear = curyear - 18;
for (maxyear; maxyear >= minyear; maxyear = maxyear - 1) {
year.options.add(new Option(maxyear, maxyear));
}
for (var mindex = 1; mindex <= 12; mindex++) {
month.options.add(new Option(mindex, mindex));
}
}
//判断是否是闰年
function leapyear(intyear) {
var result = false;
if (((intyear % 400 == 0) && (intyear % 100 != 0)) || (intyear % 4 == 0)) {
result = true;
}
else {
result = false;
}
return result;
}
//绑定天数
function addday(maxday) {
day.options.length = 1;
for (var dindex = 1; dindex <= maxday; dindex++) {
day.options.add(new Option(dindex, dindex));
}
}
function changeday() {
if (year.value == null || year.value == "") {
alert("请先选择年份！");
return false;
}
else {
if (month.value == 1 || month.value == 3 || month.value == 5 || month.value == 7 || month.value == 8 || month.value == 10 || month.value == 12) {
addday(31);
}
else {
if (month.value == 4 || month.value == 6 || month.value == 9 || month.value == 11) {
addday(30);
}
else {
if (leapyear(year.value)) {
addday(29);
}
else {
addday(28);
}
}
}
}
}
window.onload = add;
</script></td>
<td style="color:#333">（注册后不可更改）</td>
</tr>
</table>