JS获取DropDownList的value与text值

<asp:DropDownList ID="DropDownList1" runat="server" onchange="SearchChange();">
<asp:ListItem Value="0">111</asp:ListItem>
<asp:ListItem Value="1">222</asp:ListItem>
<asp:ListItem Value="2">333</asp:ListItem>
</asp:DropDownList>

<script type="text/javascript" language="javascript">
function SearchChange()
{
var ddl = document.getElementById("DropDownList1")
var index = ddl.selectedIndex;

var Value = ddl.options[index].value;
var Text = ddl.options[index].text;

alert(Value);
}
</script>