JS选取DropDownList值的例子

<script type="text/javascript" src="../Scripts/jquery-1.4.1.js"></script>
<script type="text/javascript" src="../Scripts/jquery-1.4.1.min.js"></script>
<script type="text/javascript">
 function Vl() {
 //选取DropDownList值
   var ddl = document.getElementById("DropDownList2");
   var DropDownList1_Index = ddl.selectedIndex; //获取选择项的索引
   var DropDownList1_Value = ddl.options[DropDownList1_Index].value; //获取选择项的值
   if (DropDownList1_Value == "1") {
      $(".xhcs").css('display', 'none');
    }
   else {
      $(".xhcs").css('display', 'block');
 }
 }
</script>