Question

I have two listboxes in my application on button click i am pushing the item from one list box to other , the code works fine but it causes postback , while i move the item from one list box to other whole page is being loaded again , how i can prevent this .

This will be the code on my aspx page

 <div class="bx1">
        <telerik:RadListBox ID="RadListBox1" runat="server" DataTextField="Name" DataValueField="Id"
             Width="250px">
        </telerik:RadListBox>
        </div>
       <div style="height:7px"></div>
        <div class="bx5">
         <asp:ImageButton ID="ImageButton1" runat="server" ImageUrl="images/dwnArrow.png" OnClick="MoveDownClick" />
         <asp:ImageButton ID="ImageButton2" runat="server" ImageUrl="images/uparrow.png" OnClick="MoveUpClick" />
       </div>
         <div style="height:7px"></div>

       <div class="bx1">
        <telerik:RadListBox ID="RadListBox2" runat="server"   DataTextField="Name"
            DataValueField="Id" Width="250px" >
        </telerik:RadListBox>
        </div>

This is my code behind for listbox

 protected void MoveDownClick(object sender, EventArgs e)
            {
                if (RadListBox1.SelectedIndex < 0)
                {
                }
                else
                {
                    RadListBox2.Items.Add(RadListBox1.SelectedItem);
                    RadListBox1.Items.Remove(RadListBox1.SelectedItem);
                    RadListBox2.SelectedItem.Selected = false;
                }
            }
            protected void MoveUpClick(object sender, EventArgs e)
            {
                if (RadListBox2.SelectedIndex < 0)
                {

                }
                else
                {

                    RadListBox1.Items.Add(RadListBox2.SelectedItem);
                    RadListBox2.Items.Remove(RadListBox2.SelectedItem);
                    RadListBox1.SelectedItem.Selected = false;

                }

            }

Answer 1

If your version of Visual Studio is less than 2008, then first download the ajax from the following site and install it:

http://ajaxcontroltoolkit.codeplex.com/

Add a reference to the System.Web.Extensions dll and then add the following line right after your opening <form> tag:

<asp:ScriptManager runat="server" ID="Script1"></asp:ScriptManager>

Replace the Your Code in following piece of code with your entire code that you have written above:

<asp:UpdatePanel runat="Server" ID="u1">
<ContentTemplate>
Your Code
</ContentTemplate>
</asp:UpdatePanel>

That’s it, this will stop posting back your page.