问题 I am trying to design something like the followingL <ul class="top"> <li><a href="#">Menu1</a></li> <li> <a href="#">Menu2</a> <ul class="sub"> <li><a href="#">SubMenu1</a></li> <li> <a href="#">SubMenu2</a> <ul class="subsub"> <li><a href="#">SubSubMenu1</a></li> <li><a href="#">SubSubMenu2</a></li> </ul> </li> <li><a href="#">SubMenu3</a></li> </ul> </li> <li><a href="#">Menu3</a></li> </ul> And my idea is that if the Node has subNodes, then the submenu will open. So in this instance, if