Preventing page refresh when handling MenuItemClick at server - asp.net

Question

I have a menu item that when clicked is calling a C# codebehind function.
The function doesn't get called and the whole page get refreshed.
In aspx:
<asp:Menu ID="NavigationMenu" runat="server" CssClass="menu" EnableViewState="false" IncludeStyleBlock="false" Orientation="Horizontal" onmenuitemclick="NavigationMenu_MenuItemClick">
<Items>
<asp:MenuItem Text="Item caption" Value="#" />
</Items>
</asp:Menu>
In C#:
protected void NavigationMenu_MenuItemClick(object sender, MenuEventArgs e)
{
Response.Redirect("");
SomeFunction();
}
If I'm removing the Redirect call, the page get refresh and looks like a mess.
Any advice will be welcome.

Answer 1

To get a better answer, you many want to edit your question to better explain what you are trying to accomplish.
The Menu control without the NavigateUrl attribute emits HTML that includes a list (of your menu items) with hyperlinks that perform a postback via some Javascript.
<ul class="level1">
<li>
<a class="level1selected" href="#"
onclick="__doPostBack('ctl00$MainContent$NavigationMenu','#')">
Item caption</a>
</li>
</ul>
When handling the menu click event, if your intent is to redirect the user to another page I would recommend simply setting the NavigateUrl attribute on your menu items instead of using Response.Redirect().
<asp:MenuItem Text="Item caption" Value="#" NavigateUrl="~/TargetPage.aspx" />
If you set the NavigateUrl attribute, you'll notice the onclick event doesn't even get added to the anchor tags that make up the menu item's HTML.
<ul class="level1">
<li>
<a class="level1" href="TargetPage.aspx">Item caption</a>
</li>
</ul>
If you're not intending to use the menu for navigation, but rather to perform some logic and update the page when the menu item is clicked, you may consider putting your menu in an UpdatePanel and set up the menu to trigger an async postback.
ASPX:
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="NavigationMenu" />
</Triggers>
<ContentTemplate>
<asp:Label ID="label1" runat="server"></asp:Label>
<asp:Menu ID="NavigationMenu" runat="server" CssClass="menu" EnableViewState="true" IncludeStyleBlock="false" Orientation="Horizontal" onmenuitemclick="NavigationMenu_MenuItemClick">
<Items>
<asp:MenuItem Text="Item caption" Value="#" />
</Items>
</asp:Menu>
</ContentTemplate>
</asp:UpdatePanel>
Code Behind:
protected void NavigationMenu_MenuItemClick(object sender, MenuEventArgs e)
{
SomeFunction();
}
private void SomeFunction()
{
//Performed some logic
label1.Text = "Altered the page on menu item click";
}