js取C#控件的值

var selectedValue = document.getElementById("DropDownList1").options[document.getElementById("DropDownList1").selectedIndex].value;

<script type="text/javascript">
function clean()
{

var drplZYNJ = document.getElementById("DropDownList1")
// 选择项的索引
var index = drplZYNJ.selectedIndex;
//选择项的值
var Value = drplZYNJ.options[index].value;
//选择项的内容
var Texts = drplZYNJ.options[index].text;

}
</script>

var drp = document.getElementById("DropDownList1");
if (drp.length > 0)
{
for (i=0; i < drp.options.length; i++)
{
if (drp.options(i).selected == true)
{

var a = drp.options(i).value;

}
}

<script t