如何从javascript中的radiobuttonlist中选择单选按钮

Question

  

可能重复：
  How can I determine the SelectedValue of a RadioButtonList in JavaScript?

我想在javascript中从asp.net radiobuttonlist中选择单选按钮。在textbox onchange事件中，我在下面写了代码;

<asp:RadioButtonList CssClass="radioWithProperWrap"
                  ID="RadioButtonList1" runat="server" CellPadding="0" 
            CellSpacing="0" RepeatColumns="2" RepeatDirection="Horizontal" 
                  >
            <asp:ListItem Value="1" Selected="True">Aylık Ödeyeceğim Taksite Göre</asp:ListItem>
            <asp:ListItem Value="2">Toplam Alacağım Krediye Göre</asp:ListItem>
            </asp:RadioButtonList>
<asp:TextBox ID="TempTxtBox" runat="server" onchange="myFun()" ></asp:TextBox> 

和javascript;

<script language="javascript" type="text/javascript">

    function myFun() {


        var deger = document.getElementById('<%=TempTxtBox.ClientID%>').value;
        var vade  = document.getElementById('<%=MaturitytxtBox.ClientID%>').value;


        var radioButtons = document.getElementsByName('<%=RadioButtonList1.ClientID%>');

        var radio = radioButtons.item(0).checked;

        alert(radio);

    }

</script>

它没有用。任何人都可以帮忙吗？