                        课程
                    
                        /前端开发
                        
                            /JavaScript
                        
                        /网页定位导航特效

求大神帮我找错，新手找了好几遍都找不到哪里错了。

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<title>地狗购物网——网页定位导航效果</title>
<style>
        *{ margin:0;padding:0;}
       body{font-size:12px;line-height:1.7;}
       li {list-style:none;}
        #content{width:800px;margin:0 auto;padding:20px;}
        #content h1{color:#0088bb;}
        #content .item{padding:20px;margin-bottom:20px;border:1px dotted #0088bb;}
        #content .item h2{font-size:16px;font-weight:bold;border-bottom:2px solid #0088bb;margin-bottom:10px;}
        #content .item li{display:inline;margin-right:10px;}
        #content .item li a img{width:230px;height:230px;border:none;} #menu{position:fixed;top:100px;left:50%;margin-left:400px;width:50px;}
        #menu ul li a {display:block;margin:5px 0;font-size:14px;font-weight:bold;color:#333;width:80px;height:50px;line-height:50px; text-decoration:none;text-align:center;}
        #menu ul li a:hover,#menu ul li a.current{color: #fff;background: #0088bb;}
        * html, * html body{background-image: url(about:blank);background-attachment: fixed;}
        * html #menu{position: absolute;bottom: auto;top:expression(100+((e=document.documentElement.scrollTop)?e:document.body.scrollTop)+'px');}
</style>
<script src="http://libs.baidu.com/jquery/1.10.2/jquery.js"></script>
<script>
    $(document).ready(function(){
        $(window).scroll(function(){
            //滚动条发生滚动时，要获取相应的值。
            var top=$(document).scrollTop();
            var items=$('#content').find('.item');
            var currentId="";
           var menu=$('#menu');
            //请补充此处代码，让导航菜单实现在滚动条滚动的时候自动设置焦点
            items.each(function(){
                var m=$(this);
                var itemTop=m.offset().top;
                if(top>itemTop){
                    currentId="#"+m.attr('id')
                }else{
                   return flase;
                }
            });
            //给相应楼层的a 设置 current，取消其他链接的current
            var currentLink=menu.find('.current');
            if(currentId&&currentLink.attr('href')!=currentId){
                currentLink.removeClass('current');
                menu.find('[href='+currentId+']').addClass('current');
            }
        });
    });
</script>
</head>
<body>
<div id="menu">
<ul>

<li><a href="#item1" class="current">1F 男装</a></li>
<li><a href="#item2">2F 女装</a></li>
<li><a href="#item3">3F 美妆</a></li>
<li><a href="#item4">4F 数码</a></li>
<li><a href="#item5">5F 母婴</a></li>
</ul>
</div>
<div id="content">
<h1>地狗购物网</h1>
<div id="item1" class="item">
<h2>1F 男装</h2>
<ul>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//53660fce0001111903990422.jpg" alt=""/></a></li>
</ul>
</div>
<div id="item2" class="item">
<h2>2F 女装</h2>
<ul>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//5366104c0001e5c403990422.jpg" alt=""/></a></li>
</ul>
</div>
<div id="item3" class="item">
<h2>3F 美妆</h2>
<ul>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610820001cf5b03990422.jpg" alt=""/></a></li>
</ul>
</div>
<div id="item4" class="item">
<h2>4F 数码</h2>
<ul>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610ac00012df703990422.jpg" alt=""/></a></li>
</ul>
</div>
<div id="item5" class="item">
<h2>5F 母婴</h2>
<ul>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
<li><a href="#"><img src="http://img1.sycdn.imooc.com//536610cd0001f34603990422.jpg" alt=""/></a></li>
</ul>
</div>
</div>
</body>
</html>