How do I get an Asp.Net radiobox to callback when it is clicked?

I'm working on an asp.net/C# application, and trying to get a radiobox to invoke a callback when any of the buttons on it is clicked. Does anyone know how to do this? I've tried this...

<asp:RadioButton id="id1" onclick="do_foo" runat="server" Text="Text1" GroupName="mybox" />
<asp:RadioButton id="id2" onclick="do_foo" runat="server" Text="Text2" GroupName="mybox" />
<asp:RadioButton id="id3" onclick="do_foo" runat="server" Text="Text开发者_如何学运维3" GroupName="mybox" />

and also this...

<asp:RadioButtonList onclick="do_foo" id="radiolist1" runat="server">
    <asp:ListItem>Text1</asp:ListItem>
    <asp:ListItem>Text2</asp:ListItem>
    <asp:ListItem>Text3</asp:ListItem>
</asp:RadioButtonList>

but in both cases get the error "Microsoft JScript runtime error: 'do_foo' is undefined". I know that do_foo is defined because I can invoke it from a button.

onclick="do_foo();"

Tested without the brackets and it doesn't fire.

Please include brackets after function name, It should like this

onclick="do_foo();"

You are mistaking Javascript client side function with a c# server side function.

Radio Buttons dont have a server side 'onclick' event but a client side exists so when it is clicked the browser cant find do_foo, hence the error.

You will have to use AutoPostBack="True" and the OnSelectedIndexChanged event to check which item was clicked like:

if(radiolist1.SelectedIndex==0) 
{
  //first item clicked
}
else if(radiolist1.SelectedIndex==1) 
{
  //second item clicked
}

Try this:

<asp:RadioButtonList ID="RadioButtonList1" runat="server" AutoPostBack="True" 
    onselectedindexchanged="RadioButtonList1_SelectedIndexChanged">
    <asp:ListItem>text1</asp:ListItem>
    <asp:ListItem>text2</asp:ListItem>
    <asp:ListItem>text3</asp:ListItem>
</asp:RadioButtonList>