Getting selected value from RadioButtonList in Javascript

Consider below ASP.Net RadioButtonList control:
<asp:RadioButtonList ID="rbList" runat="Server">
   <asp:ListItem Text="Kapil" Value="1" Selected="True">

   <asp:ListItem Text="Baheti" Value="2">
</asp:RadioButtonList>

You can now get selected radio button value using below javascript:
function GetRadioButtonValue()
{
  var id = <%= rbList.ClientID %>;
  var radio = document.getElementsByName(id);
  for (var i = 0; i < radio.length; i++)
     {
        if (radio[i].checked)
           alert(radio[i].value);
     }
}