Enable Disable TextBox on ASP.Net RadioButton click using Javascript

       <asp:RadioButton ID="RadioButton1" runat="server" Text = "Yes" GroupName = "Radio" onclick = "Radio_Click()" />
    <asp:RadioButton ID="RadioButton2" runat="server" Text = "No" GroupName = "Radio" onclick = "Radio_Click()" />
    <br /><asp:TextBox ID="TextBox1" runat="server" Enabled = "false"></asp:TextBox>
    <script type = "text/javascript">
        function Radio_Click() {
            var radio1 = document.getElementById("<%=RadioButton1.ClientID %>");
            var textBox = document.getElementById("<%=TextBox1.ClientID %>");
            textBox.disabled = !radio1.checked;
            textBox.focus();
        }
    </script>

Demo

Yes No