这里是一个DataList控件,当点击"查看回复"的时候TR表格的行显示出来
现在的问题是点击"查看回复"的时候在浏览器提示出s.style.display==""为空值,如何解决?请指点
<script type="text/javascript" language="javascript">
        function onoffdisplay(){
            var sub=document.getElementsByName('sub').length;
            var s=document.getElementById("scontentsub_"+sub);            
                if (s.style.display=="")
                s.style.display="none"
                else
                s.style.display=" "
                }
    </script>


<asp:DataList ID="DataListshow" runat="server">//用它生成多个表格的行
                    <ItemTemplate>
                        <tr>
                            <td bgcolor="#f3f3f3" colspan="2">
                                发表人:<%#DataBinder.Eval(Container.DataItem,"UserName") %>
                                主题：<%#DataBinder.Eval(Container.DataItem,"Subject") %>
                                于<%#DataBinder.Eval(Container.DataItem,"DataTime") %>
                            </td>
                        </tr>
                        <tr>
                            <td colspan="2">
                                发表内容:<%#DataBinder.Eval(Container.DataItem,"ContentText") %>
                                <div onclick="onoffdisplay('<%#DataBinder.Eval(Container.DataItem,"ContentID") %>')" name="sub" style="float:right;cursor:hand;">
                                    查看回复
                                </div>
                            </td>
                        </tr>
                        <tr id="scontentsub_<%#DataBinder.Eval(Container.DataItem,"ContentID") %>" style="display:none;">
                            <td bgcolor="#E3EAEB">
                                回复人：管理员 于<%#DataBinder.Eval(Container.DataItem,"RecTime") %>
                                <p>回复内容：<%#DataBinder.Eval(Container.DataItem, "Receiver")%></p>
                            </td>
                        </tr>
                    </ItemTemplate>
                    <HeaderTemplate>
                        <table align="center" cellpadding="0" cellspacing="0" width="645">
                    </HeaderTemplate>
                    <FooterTemplate>
                        </table>
                    </FooterTemplate>
                </asp:DataList>