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The OnClientSelectedIndexChanged client-side event occurs immediately after the selected item has changed.

The event handler receives two parameters:

  1. The instance of the combobox firing the event.

  2. An eventArgs parameter containing the following method:

  • get_item returns the item that has just been selected.

  • get_domEvent() returns the DOM event object.

Use this event to respond to the newly selected item:

<script language="javascript" type="text/javascript">
    function OnClientSelectedIndexChanged(sender, eventArgs) {
        var item = eventArgs.get_item();
        sender.set_text("You selected " + item.get_text());


Getting Old Value

The old selected item is available only in the OnClientSelectedIndexChanging event via the sender.get_selectedItem() method.

To have the old item in the OnClientSelectedChanged event, we can add a reference to the ComboBox client-side object in an expando property.

<script lang="javascript" type="text/javascript">  
    function OnClientSelectedIndexChanging(sender, eventArgs) {
        var oldItem = sender.get_selectedItem();
        var newItem = eventArgs.get_item();

        sender.__oldSelectedItem = oldItem;

    function OnClientSelectedIndexChanged(sender, eventArgs) {
        var oldItem = sender.__oldSelectedItem;
        var newItem = eventArgs.get_item();

        if (oldItem) {
            alert("Selection Changed from "
                + oldItem.get_text() +
                " to " +

<telerik:RadComboBox ID="RadComboBox1" runat="server" RenderMode="Lightweight" OnClientSelectedIndexChanged="OnClientSelectedIndexChanged"
        <telerik:RadComboBoxItem Text="Item 1" />
        <telerik:RadComboBoxItem Text="Item 2" />
        <telerik:RadComboBoxItem Text="Item 3" />
        <telerik:RadComboBoxItem Text="Item 4" />

See Also

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