联动的日期下拉列表，兼容IE,FF

 测试浏览器：IE7,FF3

JS代码

1. var dangQian = 31;
2.             function setDay(){
3.                 var year = parseInt(document.getElementById('year').value); //当前年
4.                 var month = parseInt(document.getElementById('month').value); //当前月
5.                 var oDay = document.getElementById('day');
6.                 var days = [31,28,31,30,31,30,31,31,30,31,30,31]; //一年中各月天数
7.                 if(year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)){ //闰年
8.                     days[1] = 29; //闰年2月29天
9.                 }
10.                 var day = days[month - 1]; //本月天数
11.                 while(dangQian > day){ //大于本月天数隐藏
12.                     oDay.removeChild(document.getElementById('day' + dangQian));
13.                     dangQian--;
14.                 }
15.                 while(day > dangQian){ //小于等于本月天数显示
16.                     dangQian++;
17.                     var option = new Option(dangQian,dangQian); //注意select动态添加option的方法
18.                     option.id = 'day' + dangQian;
19.                     oDay.options[oDay.options.length] = option; //注意select动态添加option的方法
20.                 }
21.             }
22.             
23.             function addOnload(fn){
24.                 if(typeof(fn) != 'function') return false;
25.                 var _onload = (window.onload && typeof(window.onload) == 'function') ? window.onload : null;
26.                 window.onload = function(){if(_onload)_onload();fn();};
27.             }
28.             addOnload(setDay);

jsp代码片段:

1. <select name="year" id="year" onchange="setDay()">
2.                                 <%for(int i = 0,len = 10; i < len; i++){%>
3.                                     <option value="<%=y-i %>" <%if(y-i == year){out.print("selected");} %>><%=y-i %></option>
4.                                 <%}%>
5.                                 </select>
6.                                 <select name="month" id="month" onchange="setDay()">
7.                                 <%for(int i = 0,len = 12; i < len; i++){%>
8.                                     <option value="<%=(i+1)<10?"0"+(i+1):(i+1) %>" <%if(i+1 == month){out.print("selected");} %>><%=i+1 %></option>
9.                                 <%}%>
10.                                 </select>
11.                                 <select name="day" id="day">
12.                                 <%for(int i = 0,len = 31; i < len; i++){%>
13.                                     <option id="day<%=(i+1) %>" value="<%=(i+1)<10?"0"+(i+1):(i+1) %>" <%if(i+1 == day){out.print("selected");} %>><%=i+1 %></option>
14.                                 <%}%>
15.                                 </select>