随便贴的，呵呵！刚刚贴了一次，快要好了，浏览器死掉了,郁闷！这次就更随便了

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

    $(document).ready(function() {

        var SelectedCls = "<%=ClsId%>";//后台传过来的，这个是为了有个初始选中的项

        var TitleObj = $("#menu .menuTitle");
        TitleObj.each(function(i) {
            if (TitleObj.eq(i).attr('id') == SelectedCls) {
                TitleObj.eq(i).next().show();
            }
            else {
                TitleObj.eq(i).next().hide();
            }
        });

    });

    function OpenMenu(objId) {
        var TargetId = objId;
        var TitleObj = $("#menu .menuTitle");

        TitleObj.each(function(i) {

            var oL = $("#L" + TitleObj.eq(i).attr('id'));
            var oR = $("#R" + TitleObj.eq(i).attr('id'));

            if (TitleObj.eq(i).attr('id') == TargetId) {
                oL.removeClass("menuTitleL2").addClass("menuTitleL1");//这里采用.号分隔函数的用法，使两个函数联合起来用
                oR.removeClass("menuTitleR2").addClass("menuTitleR1");
                TitleObj.eq(i).next().show();
            }
            else {
                oL.removeClass("menuTitleL1").addClass("menuTitleL2");
                oR.removeClass("menuTitleR1").addClass("menuTitleR2");
                TitleObj.eq(i).next().hide();
            }
        });
    }
</script>

   <div id="menu">
        <asp:Repeater ID="MenuItemRepeater" runat="server" OnItemDataBound="MenuItemRepeater_ItemDataBound">
            <ItemTemplate>
                <div class="menuTitle" id="<%#Eval("F_Id").ToString()%>" onclick="javascript:OpenMenu(this.id)">
                    <div class="menuTitleL2" id="L<%#Eval("F_Id").ToString()%>">
                    </div>
                    <div class="menuTitleC">
                        <%#Eval("F_ClassName")%></div>
                    <asp:HiddenField runat="server" ID="hdClsId" Value='<%#Eval("F_Id").ToString()%>' />
                    <div class="menuTitleR2" id="R<%#Eval("F_Id").ToString()%>">
                    </div>
                </div>
                <div class="menuBody" id="menuBody<%#Eval("F_Id").ToString()%>">
                    <ul>
                        <asp:Repeater ID="HelpItemList" runat="server">
                            <ItemTemplate>
                                <li><a href="?Id=<%#Eval("F_Id")%>&ClsId=<%#Eval("F_ClsId")%>">
                                    <%#Eval("F_Title")%></a></li>
                            </ItemTemplate>
                        </asp:Repeater>
                    </ul>
                </div>
            </ItemTemplate>
        </asp:Repeater>
    </div>