//自动生成年月日
function createSelect(af)
{
var Years = document.getElementById("birthyear");
var Months = document.getElementById("birthmonth");
var Days = document.getElementById("birthday");
var dt = new Date();
if(af == 1)
{
MaxYear = dt.getFullYear();
MinYear = dt.getFullYear()-50;
for(var i = MinYear; i <= MaxYear; i++)
{
var op = document.createElement("OPTION");
op.value = i;
op.innerHTML = i;
Years.appendChild(op);
}
Years.selectedIndex = 0;
for(var i = 1; i < 13; i++)
{
var op = document.createElement("OPTION");
op.value = i;
op.innerHTML = i;
Months.appendChild(op);
}
Months.selectedIndex = 0;
}
var date = new Date(Years.value, Months.value, 0);
var daysInMonth = date.getDate();
Days.options.length = 0;
for(var i = 1; i <= daysInMonth ; i++)
{
var op = document.createElement("OPTION");
op.value = i;
op.innerHTML = i;
Days.appendChild(op);
}
Days.selectedIndex = 0;
}
在页面调用
<select id="birthyear" name="birthyear" size="1" onChange="createSelect()"></select>
<select id="birthmonth" name="birthmonth" size="1" onChange="createSelect()"></select>
<select id="birthday" name="birthday" size="1" ></select>
<script type="text/javascript">createSelect(1);</script>