Focusing on the First Element in RadComboBox on Expand

Environment

Product	Version
RadComboBox for ASP.NET AJAX	all

Description

When expanding a RadComboBox, I want the focus to automatically move to the first item in the dropdown list.

This KB article also answers the following questions:

• How can I automatically highlight the first item in a RadComboBox when it is expanded?
• What client-side event allows me to set focus to the first item in a RadComboBox?
• How to improve user experience by focusing on the first item in RadComboBox dropdown?

Solution

To focus on the first item of a RadComboBox when it is expanded, leverage the OnClientDropDownOpened event. In this event, programmatically set the focus and highlight the first item using JavaScript. Follow the steps below:

1. Define the RadComboBox in your ASP.NET page with the OnClientDropDownOpened event, pointing to a JavaScript function.

   ASPX

   <telerik:RadComboBox ID="RadComboBox1" runat="server" OnClientDropDownOpened="onDropDownOpened">
       <Items>
           <telerik:RadComboBoxItem Text="Item 1" />
           <telerik:RadComboBoxItem Text="Item 2" />
           <telerik:RadComboBoxItem Text="Item 3" />
       </Items>
   </telerik:RadComboBox>

2. Implement the JavaScript function referenced in the OnClientDropDownOpened event. This function should:

   • Retrieve the RadComboBox instance.
   • Check if there are any items in the RadComboBox.
   • Highlight the first item and set focus to the RadComboBox input element.
   JavaScript

   <script type="text/javascript">
       function onDropDownOpened(sender, eventArgs) {
           var comboBox = sender;
           var items = comboBox.get_items();
           if (items.get_count() > 0) {
               var firstItem = items.getItem(0);
               firstItem.highlight();
               comboBox.get_inputDomElement().focus();
           }
       }
   </script>

This code ensures that whenever the RadComboBox dropdown is expanded, the focus will be on the first item, enhancing the user experience by providing a smoother interaction.

See Also

• RadComboBox Client-Side Programming
• OnClientDropDownOpened Event