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>