There are a few solutions to this problem.
One of the simpler would be to move the name into a JavaScript variable since the problem only occurs within the control when trying to evaluate txt_name.ClientID inside the OnClientClick attribute of an ASP.NET control.
<script>
var txtName = '<%= txt_name.ClientID %>';
</script>
Enter server name: <asp:TextBox ID="txt_name" runat="server"></asp:TextBox>
<asp:Button ID="btn_view" runat="server" OnClick="View_btn_click"
OnClientClick="return AlertOnGo('View Configuration',
document.getElementById(txtName).value)" Text ="GO!" />