<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

<head>
<title>年月日三下拉框联动</title>
<meta http-equiv='Content-Type' content='text/html; charset=gb2312'>
</head>

<body>
<form name="reg_testdate">
  <select name="YYYY" onchange="YYYYDD(this.value)">
    <option value="">请选择 年</option>
  </select>
  <select name="MM" onchange="MMDD(this.value)">
    <option value="">选择 月</option>
  </select>
  <select name="DD">
    <option value="">选择 日</option>
  </select>
</form>
<script language="JavaScript"><!--  
   function YYYYMMDDstart()  
   {  
           MonHead = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];  
   
           //先给年下拉框赋内容  
           var y  = new Date().getFullYear();  
           for (var i = (y-30); i < (y+30); i++) //以今年为准,前30年,后30年  
                   document.reg_testdate.YYYY.options.add(new Option(" "+ i +" 年", i));  
   
           //赋月份的下拉框  
           for (var i = 1; i < 13; i++)  
                   document.reg_testdate.MM.options.add(new Option(" " + i + " 月", i));  
   
           document.reg_testdate.YYYY.value = y;  
           document.reg_testdate.MM.value = new Date().getMonth() + 1;  
           var n = MonHead[new Date().getMonth()];  
           if (new Date().getMonth() ==1 && IsPinYear(YYYYvalue)) n++;  
                writeDay(n); //赋日期下拉框Author:meizz  
           document.reg_testdate.DD.value = new Date().getDate();  
   }  
   if(document.attachEvent)  
       window.attachEvent("onload", YYYYMMDDstart);  
   else  
       window.addEventListener('load', YYYYMMDDstart, false);  
   function YYYYDD(str) //年发生变化时日期发生变化(主要是判断闰平年)  
   {  
           var MMvalue = document.reg_testdate.MM.options[document.reg_testdate.MM.selectedIndex].value;  
           if (MMvalue == ""){ var e = document.reg_testdate.DD; optionsClear(e); return;}  
           var n = MonHead[MMvalue - 1];  
           if (MMvalue ==2 && IsPinYear(str)) n++;  
                writeDay(n)  
   }  
   function MMDD(str)   //月发生变化时日期联动  
   {  
        var YYYYvalue = document.reg_testdate.YYYY.options[document.reg_testdate.YYYY.selectedIndex].value;  
        if (YYYYvalue == ""){ var e = document.reg_testdate.DD; optionsClear(e); return;}  
        var n = MonHead[str - 1];  
        if (str ==2 && IsPinYear(YYYYvalue)) n++;  
       writeDay(n)  
   }  
   function writeDay(n)   //据条件写日期的下拉框  
   {  
           var e = document.reg_testdate.DD; optionsClear(e);  
           for (var i=1; i<(n+1); i++)  
                e.options.add(new Option(" "+ i + " 日", i));  
   }  
   function IsPinYear(year)//判断是否闰平年  
   {     return(0 == year%4 && (year%100 !=0 || year%400 == 0));}  
   function optionsClear(e)  
   {  
        e.options.length = 1;  
   }  
   //--></script>
</body>
</html>

04-13 16:31