JS模拟的QQ面板上的多级可展开的菜单

<title>QQ菜单</title> <style> body { font-family: verdana, helvetica, arial, sans-serif; } #mainMenu { background-color: #EEE; border: 1px solid #CCC; color: #000; width: 203px; } #menuList { margin: 0px; padding: 10px 0px 10px 15px; } li.menubar { background: url() no-repeat 0em 0.3em; font-size: 12px; line-height: 1.5em; list-style: none outside; } .menu, .submenu { display: none; margin-left: 15px; padding: 0px; } .menu li, .submenu li { background: url() no-repeat 0em 0.3em; list-style: none outside; } a.actuator { background-color: transparent; color: #000; font-size: 12px; padding-left: 15px; text-decoration: none; } a.actuator:hover { text-decoration: underline; } .menu li a, .submenu li a { background-color: transparent; color: #000; font-size: 12px; padding-left: 15px; text-decoration: none; } .menu li a:hover, submenu li a:hover { text-decoration: underline; } span.key { text-decoration: underline; } </style> <div> <ul> <li> 我有朋友圈 <ul> <li> 我的好友 <ul> <li>张三[10000001]</li> <li>李四[10000002]</li> <li>李四[10000002]</li> </ul> </li> <li> 陌生人 <ul> <li>张三[10000001]</li> <li>李四[10000002]</li> </ul> </li> </ul> </li> </ul> </div>