OnClientDropDownOpened

The OnClientDropDownOpened client-side event occurs after the drop-down list has been opened.

The event handler receives two parameters:

1. The instance of the DropDownList firing the event.

2. An eventArgs parameter which does not have methods.

You can use this event to perform any client-side actions when the drop-down is completely opened:

ASPNET

<script type="text/javascript">
    function OnClientDropDownOpenedHandler(sender, eventArgs) {
        alert("The dropdown is opened now");
    }
</script>
<telerik:RadDropDownList
    ID="RadDropDownList1"
    OnClientDropDownOpened="OnClientDropDownOpenedHandler"
    runat="server">
</telerik:RadDropDownList>