问题是这样的 我要从后台获取asp:RadioButton 是否被选中

 <script type="text/javascript">
    function selectSingleRadio(rbtn) {
        var radio = document.getElementsByTagName("radio");
        var arrAll = document.all;

        for (i = 0; i < arrAll.length; i++) {
            if (arrAll[i].type == "radio") {
                arrAll[i].checked = true;
            }
        }
        rbtn.checked = false;
        console.log(rbtn.checked);
    }       
</script> 
</section>
    <div style="background-color: red; padding-top:70xp">
        <div style="float: right; margin-right: 100px; margin-top: 30px;">
            <a data-toggle="modal"  data-target="#Signup"  href="#"><font style="font-size: 24px;">新建</font></a><font style="font-size: 24px;">丨
                <a data-toggle="modal"  data-target="#Signup"  href="#"><font style="font-size: 24px;">上传</font></a>丨
                <a   href="#"><font style="font-size: 24px;">

                        <asp:Button ID="Button2"  runat="server" Text="删   除"   OnClick="Button2_Click" />


                              </font></a></font>
        </div>
    </div>
        <div style="float: left; margin-left: 20%;margin-right: 10%; margin-top: 10px; ">  
    <div class="row">
            <asp:Repeater ID="Modertuiji" runat="server">

                     <ItemTemplate>  

                        <div class="col-md-4 col-sm-6 col-xs-12" >


                            <div class="thumbnail">

                             <table  style=" font-family: '微软雅黑'; text-align: center; margin: auto 0;">
                             <tr>
                              <asp:RadioButton runat="server"  ID="rdo1"  HidText='<%#Eval("FileName") %>'  onclick="selectSingleRadio(this);"  />
                                 <td  style="width:250px;"><a href="#"><img height="120" width="130"  class =""  style="height:120px;width:130px" src="<%#Eval("ImgPath") %>"/></a></td>
                                  <td><br /></td>

                            </tr>
                              <tr style="font: '微软雅黑'; font-size: 24px;">
                                 <td style="width: 250px;"><font><%#Eval("FileName") %></font> </td>
                              </tr>

                            </table>
                            </div>
                           </div>
                                     </div>

                                  </div>
                                </div>
                            </div>--%>
                     </ItemTemplate>
            </asp:Repeater>

        </div>
    </div>

没有radio这种标签，是input
var radio = document.getElementsByTagName("input");