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Version Q2 2011 released 07/12/2011
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ComboBox / Client-side Events

Logged events
Clear log Event log:

  • RadComboBox provides a rich set of client-side events. Here's a list of all client-side events exposed by the combobox:

    • OnClientSelectedIndexChanging
    • OnClientSelectedIndexChanged
    • OnClientDropDownClosing
    • OnClientDropDownOpening
    • OnClientItemsRequested
    • OnClientItemsRequesting
    • OnClientItemBlur
    • OnClientItemBlur
    • OnClientFocus
    • OnClientKeyPressing
    • OnClientCallBackError

    The client-side events are directly assigned to the combobox control as for an example:

        <telerik:radcombobox

              ...

              OnClientSelectedIndexChanged = "OnClientSelectedIndexChangedEventHandler" />
    All client side events take two parameters - sender and arguments:
            function OnClientSelectedIndexChangedEventHandler(sender, args) 

            {

                //sender represents the combobox that has fired the event
            //the code below obtains the item that has been changed
            var item = args.get_item();

             }

    All events that end in "ing" (i.e. OnClientSelectedIndexChanging)" can be cancelled. To do this you should call the set_cancel(true) method in the event handler: 

             function HandleStartChanging(sender, args)

             {                            
	    set_cancel(true);                  
         }

    Once, the OnClientSelectedIndexChanging event is cancelled, no other items can be selected.

Source Code

C# VB.NET
Show code in new window Demo isolation steps
  • <%@ Page AutoEventWireup="true" CodeFile="DefaultVB.aspx.vb" Inherits="Telerik.ComboboxExamplesVB.ClientEvents.DefaultVB"
        Language="vb" %>

    <%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
    <%@ Register TagPrefix="qsf" Namespace="Telerik.QuickStart" %>
    <%@ Register TagPrefix="qsf" TagName="Header" Src="~/Common/Header.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="HeadTag" Src="~/Common/HeadTag.ascx" %>
    <%@ Register TagPrefix="qsf" TagName="Footer" Src="~/Common/Footer.ascx" %>


    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head id="Head1" runat="server">
        <qsf:HeadTag ID="Headtag1" runat="server" />
        
        <link rel="stylesheet" type="text/css" href="styles.css" />
    </head>
    <body class="BODY">
        <form id="mainForm" method="post" runat="server">
            <qsf:Header ID="Header1" runat="server" NavigationLanguage="VB" />
            
            <telerik:RadScriptManager ID="RadScriptManager1" runat="server" />
            
            <telerik:RadAjaxPanel ID="RadAjaxPanel1" runat="server">
                <qsf:ConfiguratorPanel runat="server" ID="ConfigurationPanel1" Title="Logged events" Expanded="true">
                    <ul style="margin-left: 0; border-left: none">
                        <li>
    <asp:CheckBox ID="DropDownOpening" runat="server" Text="OnClientDropDownOpening"
    AutoPostBack="True" Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="DropDownOpened" runat="server" Text="OnClientDropDownOpened" AutoPostBack="True"
    Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="DropDownClosing" runat="server" Text="OnClientDropDownClosing"
    AutoPostBack="True" Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="DropDownClosed" runat="server" Text="OnClientDropDownClosed" AutoPostBack="True"
    Checked="True" />
                        </li>
                    </ul>
                    <ul>
                        <li>
    <asp:CheckBox ID="SelectedIndexChanging" runat="server" Text="OnClientSelectedIndexChanging"
    AutoPostBack="True" Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="SelectedIndexChanged" runat="server" Text="OnClientSelectedIndexChanged"
    AutoPostBack="True" Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="ItemsRequesting" runat="server" Text="OnClientItemsRequesting"
    AutoPostBack="True" Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="ItemsRequested" runat="server" Text="OnClientItemsRequested" AutoPostBack="True"
    Checked="True" />
                        </li>
                    </ul>
                    <ul>
                        <li>
    <asp:CheckBox ID="KeyPressing" runat="server" Text="OnClientKeyPressing" AutoPostBack="True"
    Checked="True" />
                        </li>
                        <li>
    <asp:CheckBox ID="TextChange" runat="server" Text="OnClientTextChange" AutoPostBack="True"
    Checked="True" />
                        </li>
                    </ul>
                </qsf:ConfiguratorPanel>
                
                <telerik:RadComboBox
                    ID="RadComboBox1" runat="server"
                    Height="170px" Width="204px"
                    ShowMoreResultsBox="True"
                    EnableLoadOnDemand="True"
                    OnItemsRequested="RadComboBox1_ItemsRequested"
                    style="margin: 20px auto; display:block !important;" />

            </telerik:RadAjaxPanel>
            
            <qsf:EventLogConsole ID="EventLogConsole1" runat="server" AllowClear="true" />

            <script type="text/javascript">
                function onDropDownOpening(sender)
                {
                    logEvent("Drop Down opening");
                }

                function onDropDownOpened(sender)
                {
                    logEvent("Drop Down opened");
                }

                function onDropDownClosing(sender)
                {
                    logEvent("Drop Down closing");
                }

                function onDropDownClosed(sender)
                {
                    logEvent("Drop Down closed");
                }

                function onSelectedIndexChanging(sender, eventArgs)
                {
                 var item = eventArgs.get_item();
                
                    var selectedItem = sender.get_selectedItem();
                    var previouslySelectedItemText = selectedItem != null ? selectedItem.get_text() : sender.get_text();
                    
                    logEvent("Changing from Item '" + previouslySelectedItemText + "'");
                }

                function onSelectedIndexChanged(sender, eventArgs)
                {
                    var selectedItem = eventArgs.get_item();
                    var selectedItemText = selectedItem != null ? selectedItem.get_text() : sender.get_text();
                    
                    logEvent("Changed to Item '" + selectedItemText + "'");
                }

                function onItemsRequesting(sender, eventArgs)
                {
                    logEvent("Requesting Items with text '"+ eventArgs.get_text()+"'");
                }
                
                function onItemsRequested(sender, eventArgs)
                {
                    logEvent("Items requested with text '"+ eventArgs.get_text()+"'");
                }

                function onKeyPressing(sender, eventArgs)
                {
                    logEvent("Pressed key code: "+ eventArgs.get_domEvent().keyCode);
                }

                function onTextChange(sender)
                {
                    logEvent("Text changed to: "+ sender.get_text());
                }
            </script>
            
            <qsf:Footer runat="server" ID="Footer1" />
        </form>
    </body>
    </html>

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