RadComboBox supports a number of client-side events that let you customize its behavior:

• OnClientItemsRequestFailed occurs when the load-on-demand callback error appears.
• OnClientBlur occurs when RadComboBox loses focus.
• OnClientDropDownOpening occurs before the drop-down list opens.
• OnClientDropDownOpened occurs after the drop-down list has been opened.
• OnClientDropDownClosing occurs before the drop-down list closes.
• OnClientDropDownClosed occurs after the drop-down has been closed.
• OnClientFocus occurs when RadComboBox has just received input focus.
• OnClientItemsRequesting occurs when the user triggers the load-on-demand mechanism by typing in the input area or clicking the drop-down toggle of RadComboBoxx. This event fires before the items are added.
• OnClientItemsRequested occurs immediately after the load-on-demand mechanism has bound new items to RadComboBox.
• OnClientKeyPressing occurs when a RadComboBox item is selected and the user presses a key.
• OnClientSelectedIndexChanging occurs before the selected item is changed in response to a user action.
• OnClientSelectedIndexChanged occurs after the selected item has been changed in response to a user action.
• OnClientItemChecking occurs when a particular item is about to be checked.
• OnClientItemChecked occurs after the selected item has been changed in response to a user action.
• OnClientLoad occurs after the RadComboBox has been fully initialized on the client-side.
• OnClientTextChange occurs when the text in the input area has been changed.
• OnClientItemDataBound occurs for each item that is created during Web Service Load on Demand (available after Q3 SP2 2008).

To use these events, simply write a JavaScript function that can be called when the event occurs. Then assign the name of the JavaScript function as the value of the the corresponding RadComboBox property.

CopyASPX

<script language="javascript" type="text/javascript">
    function MyClientBlur(sender, eventArgs) {
        alert("blur");
    }
</script>

<telerik:radcombobox 
    id="RadComboBox1" 
    runat="server" 
    onclientblur="MyClientBlur">
</telerik:radcombobox>

You can also assign event handlers in client-side code:

CopyJavaScript

function MyClientBlur(sender, eventArgs) {
    alert("blur");
}

function pageLoad() {
    var combo = $find("<%= RadComboBox1.ClientID %>");
    combo.add_onClientBlur(MyClientBlur);
}

Another advantage of the client-side API is that you can detach an event handler dynamically:

CopyJavaScript

function RemoveEventHandler() {
    var combo = $find("<%= RadComboBox1.ClientID %>");
    combo.remove_onClientBlur(MyClientBlur); 
}

Note that on the client-side, the names of events are slightly different than on the server side. The following table shows the correspondance between client-side and server-side names:

For a live example of using client-side events, see Client Events.