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The OnClientDropDownClosing client-side event occurs before the drop-down list closes.

The event handler receives two parameters:

  1. The instance of the DropDownList firing the event.

  2. An eventArgs parameter containing the following methods:

    • set_cancel lets you prevent the drop-down from closing.

The following example uses the OnClientDropDownClosing event to prevent the drop-down list from closing if the prompt item is selected:

<script type="text/javascript">
    function OnClientDropDownClosing(sender, eventArgs) {
        if (sender.get_selectedItem().get_text() == "Select An Item") {
        else {

<telerik:RadDropDownList RenderMode="Lightweight" runat="server" ID="RadDropDownList1" OnClientDropDownClosing="OnClientDropDownClosing">
        <telerik:DropDownListItem runat="server" Text="Select An Item" />
        <telerik:DropDownListItem runat="server" Text="Item 1" />
        <telerik:DropDownListItem runat="server" Text="Item 2" />
        <telerik:DropDownListItem runat="server" Text="Item 3" />
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