常用的左侧导航效果，JS简单，为提高导航性能而生，各位可以 参考应用。
效果展示：
HTML:
<!--左侧菜单--> <div class="menu"> <ul class="menu_list"> <li class="even"> <p class="menu_title bgfs"><a href="#" target="_blank">服饰箱包</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> <li class="odd"> <p class="menu_title bgjs"><a href="#" target="_blank">酒水饮料</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> <li class="even"> <p class="menu_title bgjj"><a href="#" target="_blank">居家建材</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> <li class="odd"> <p class="menu_title bgcy"><a href="#" target="_blank">餐饮娱乐</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> <li class="even"> <p class="menu_title bgmr"><a href="#" target="_blank">美容保健</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> <li class="odd"> <p class="menu_title bgjy"><a href="#" target="_blank">教育培训</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a> </p> </li> <li class="even"> <p class="menu_title bggyp"><a href="#" target="_blank">工业品</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a> </p> </li> <li class="odd"> <p class="menu_title bgxqt"><a href="#" target="_blank">新奇特</a></p> <p class="menu_sort"> <a href="#" target="_blank">女装</a><a href="#" target="_blank">男装</a><a href="#" target="_blank">童装</a><a href="#" target="_blank">包包</a><br/> <a href="#" target="_blank">鞋</a><a href="#" target="_blank">饰品</a> </p> </li> </ul> <div class="menu_box hide"> <div class="menu_cont hide"> <div class="menu_cont01"> <span class="menu_title_video">项目视频</span> <div class="menu_video"> <ul> <li><a href="#" target="_blank"><img src="images/ad/home_53.gif" /></a></li> <li><a href="#" target="_blank"><img src="images/ad/home_53.gif" /></a></li> <li><a href="#" target="_blank"><img src="images/ad/home_53.gif" /></a></li> <li><a href="#" target="_blank"><img src="images/ad/home_53.gif" /></a></li> <li><a href="#" target="_blank"><img src="images/ad/home_53.gif" /></a></li> </ul> </div> <div class="scroll_menu"> <span class="prev_menu" href="#"></span> <span class="next_menu" href="#"></span> <div class="roolbox_menu"> <div class="scroll_list_menu"> <ul> <li> <p class="ad_logo ad_fs01"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </p> <p class="ad_logo"> <span class="ad_fs02"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </span> <span class="ad_fs03"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </span> </p> <p class="ad_logo ad_fs04"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </p> <p class="ad_logo"> <span class="ad_fs02"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> <span class="ad_fs03"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> </p> <p class="ad_logo"> <span class="ad_fs05"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> <span class="ad_fs06"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> </p> </li> <li> <p class="ad_logo ad_fs01"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </p> <p class="ad_logo"> <span class="ad_fs02"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </span> <span class="ad_fs03"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名" /></a> </span> </p> <p class="ad_logo ad_fs04"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </p> <p class="ad_logo"> <span class="ad_fs02"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> <span class="ad_fs03"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> </p> <p class="ad_logo"> <span class="ad_fs05"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> <span class="ad_fs06"> <a href="#" target="_blank"><img src="images/ad/home_88.jpg" alt="项目名"/></a> </span> </p> </li> </ul> </div> </div> </div> <div class="menupic_fsxb"><img src="images/pic_fsxb.png" /></div> </div> </div> <div class="menu_cont hide">2</div> <div class="menu_cont hide">3</div> <div class="menu_cont hide">4</div> <div class="menu_cont hide">5</div> <div class="menu_cont hide">6</div> <div class="menu_cont hide">7</div> <div class="menu_cont hide">8</div> </div> </div> <!--中间项目展示-->
JS：
$(".menu_list li").mouseenter(function(){
$(".menu_box").show();
var nav_index = $(".menu_list li").index(this);
$(".menu_cont").eq(nav_index).show()//滑动菜单对应当前内容
.siblings().hide();
}) ;
$(".menu").mouseleave(function(){
$(".menu_box").hide();
}) ;