RadComboBox for ASP.NET AJAX
Contents
RadControls for ASP.NET AJAX

Consider the following scenario.

  1. There is Telerik RadComboBox on your page

  2. The combobox loads its items on demand - in the ItemsRequested event handler (EnableLoadOnDemand is enabled)

  3. The items should be loaded only when more than 3 characters are entered in the input field

CopyASPX
<telerik:radcombobox 
    id="RadComboBox1" 
    runat="server" 
    enableloadondemand="True" 
    onclientitemsrequesting="OnClientItemsRequestingHandler"
    onitemsrequested="RadComboBox1_ItemsRequested">
</telerik:radcombobox>
CopyJavaScript
function OnClientItemsRequestingHandler(sender, eventArgs) 
{
    if (sender.get_text().length < 3) 
    {
        eventArgs.set_cancel(true);
    } 
}