<script>function CheckDays()
{
switch(parseInt(document.all.BirthMonth.value) )//==================
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
SetDays(31);
break;
case 2:
if((document.all.BirthYear.value%4==0 && document.all.BirthYear.value %100!=0) || (document.all.BirthYear.value %400==0)) SetDays(29);
else SetDays(28);
break;
case 4:
case 6:
case 9:
case 11:
SetDays(30);break;
default:alert("This is a Problem"); //==================
}
function SetDays(days)
{
var optD=document.all.BirthDay;
optD.options.length=0;//==================
for(var i=1;i <=days;i++)
{
optD.add(new Option(i,i));
}
}
}
</script>
<body>
<select name="BirthYear" id="birthdate" style="width:10%">
<script language="javascript">
var optY=document.all.BirthYear; var year=new Date().getYear()
for(var i=1990;i <=year;i++)
{
optY.add(new Option(i,i));
}
</script>
</select>
<select name="BirthMonth" id="birthmonth" style="width:5%" onchange="javascript:CheckDays();">
<script language="javascript"> var optM=document.all.BirthMonth;
for(var j=1;j <=12;j++)
{
optM.add(new Option(j,j));
}
</script>
</select>
<select name="BirthDay" id="birthday" style="width:5%">
</select>
</body>
</html>
{
switch(parseInt(document.all.BirthMonth.value) )//==================
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
SetDays(31);
break;
case 2:
if((document.all.BirthYear.value%4==0 && document.all.BirthYear.value %100!=0) || (document.all.BirthYear.value %400==0)) SetDays(29);
else SetDays(28);
break;
case 4:
case 6:
case 9:
case 11:
SetDays(30);break;
default:alert("This is a Problem"); //==================
}
function SetDays(days)
{
var optD=document.all.BirthDay;
optD.options.length=0;//==================
for(var i=1;i <=days;i++)
{
optD.add(new Option(i,i));
}
}
}
</script>
<body>
<select name="BirthYear" id="birthdate" style="width:10%">
<script language="javascript">
var optY=document.all.BirthYear; var year=new Date().getYear()
for(var i=1990;i <=year;i++)
{
optY.add(new Option(i,i));
}
</script>
</select>
<select name="BirthMonth" id="birthmonth" style="width:5%" onchange="javascript:CheckDays();">
<script language="javascript"> var optM=document.all.BirthMonth;
for(var j=1;j <=12;j++)
{
optM.add(new Option(j,j));
}
</script>
</select>
<select name="BirthDay" id="birthday" style="width:5%">
</select>
</body>
</html>
<select name="BirthDay" id="birthday" style="width:5%"> 这个下拉框没有任何数据