一个循环判断当前滚动到的位置，另一个循环遍历导航条判断其id是否与滚动到的位置相同
效果如图：
实现代码：
<!DOCTYPE html> <html> <head lang="en"> <meta charset="UTF-8"> <title>地狗购物网--网页定位导航效果</title> <style type="text/css"> *{ 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: 12px; font-weight: bold; border-bottom: 2px solid #0088bb; margin-bottom: 10px; } #content .item li{ display: inline; margin-left:10px ; } #content .item li a img{ width: 230px; height: 230px; border: none; } #menu{ position: fixed; top: 100px; left: 50%; margin-left: 400px; width: 80px; } #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-align: center; text-decoration: none; } #menu ul li a:hover{ color: #fff; background: #0088bb; } #menu ul li .current{ color: #fff; background: #0088bb; } </style> <script type="text/javascript"> window.onload = function(){ window.onscroll=function(){ var top = document.documentElement.scrollTop || document.body.scrollTop; var menus = document.getElementById("menu").getElementsByTagName("a"); var items=document.getElementById("content").getElementsByClassName("item"); var currentId=""; for(var i=0;i<items.length;i++){ var _item=items[i]; var _itemTop = _item.offsetTop; if(top>_itemTop - 200){ currentId=_item.id; }else{ break; } } if(currentId!=""){ //给正确的menu下的a元素class赋值 for(var j=0;j<menus.length;j++){ var _menu=menus[j]; var _href=_menu.href.split("#");//因为只通过href获取的链接为一长串链接，需要通过#分成数组 if(_href[_href.length-1]!=currentId){ _menu.className = ""; }else{ _menu.className = " current"; } } } } } </script> </head> <body> <div> <ul> <li><a href="#item1">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> <h1>地狗购物网</h1> <div> <h2>1F 男装</h2> <ul> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/1F.jpg" alt=""/></a></li> </ul> </div> <div> <h2>2F 女装</h2> <ul> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/2F.jpg" alt=""/></a></li> </ul> </div> <div> <h2>3F 美妆</h2> <ul> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/3F.jpg" alt=""/></a></li> </ul> </div> <div> <h2>4F 数码</h2> <ul> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/4F.png" alt=""/></a></li> </ul> </div> <div> <h2>5F 母婴</h2> <ul> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> <li><a href="#"><img src="https://www.jb51.net/img/5F.jpg" alt=""/></a></li> </ul> </div> </div> </body> </html>