问下拉列表控件的值更改时的确认

EN

<asp:DropDownList ID="ddlConfirm" runat="server" OnChange="ddlConfirmClick()">
</asp:DropDownList>
function ddlConfirmClick() {
   if ($('#<%= ddlConfirm.ClientID %>').val() == "NO") {
      if(confirm("Are you sure you want to continue?")){
         // do something.
      }
   }
}

<script type='text/javascript'>
    window.onload = function() { HookUpEvent(); }

    function HookUpEvent()
    {
        var comboBox= document.getElementById ( "MyComboId" );
        comboBox.onchange = function () { OnComboSelected( this ); }
    }

    function OnComboSelected(selectedElement)
    {
        if(selectedElement.value == 'No')
        {
           alert('Your warning message!');
        } 
        return false;  
    }
</script>

    $('#<%= ddlConfirm.ClientID %>').change(function(){
        //on-change code goes in here.
        if (this.val() == "NO") {
        alert("message")
}
    });