javascript 日期下拉列表

javascript 日期下拉列表
<script type="text/javascript">
function createSelect(ActionFlag)
{
   var selYear = document.getElementById("tYEAR");
   var selMonth = document.getElementById("tMON");
   var selDay = document.getElementById("tDAY");
   var dt = new Date();
 
   if(ActionFlag == 1)
   {
    MaxYear = dt.getFullYear();
    MinYear = dt.getFullYear()-100;
 
    for(var i = MinYear; i <= MaxYear; i++)
    {
     var op = document.createElement("OPTION");
     op.value = i;
     op.innerHTML = i;
     selYear.appendChild(op);
    }
    selYear.selectedIndex = 0;
  
    for(var i = 1; i < 13; i++)
    {
     var op = document.createElement("OPTION");
     op.value = i;
     op.innerHTML = i;
     selMonth.appendChild(op);
    }
    selMonth.selectedIndex = dt.getMonth();
   }
 
   var date = new Date(selYear.value, selMonth.value, 0);
   var daysInMonth = date.getDate();
   selDay.options.length = 0;
 
   for(var i = 1; i <= daysInMonth ; i++)
   {
    var op = document.createElement("OPTION");
    op.value = i;
    op.innerHTML = i;
    selDay.appendChild(op);
   }
   //alert();
   selDay.selectedIndex = dt.getDate() - 1;
}
</script>
   <select id="tYEAR" name="tYEAR" size="1" onChange="createSelect()"></select>年
   <select id="tMON" name="tMON" size="1" onChange="createSelect();"></select>月
   <select id="tDAY" name="tDAY" size="1" ></select>日 *
<script type="text/javascript">createSelect(1);</script>