JS+CSS实现鼠标悬停动态翻滚导航条

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>动态翻滚的导航条</title>
<style type="text/css">
.clear:after{content:"."; display:block; height:0; clear:both; visibility:hidden}.clear{display:inline-block}.clear{display:block}
div#nav{height:32px; background:url(images/YL29.jpg) repeat-x}
div#nav ul{
  width:705px;
  list-style:none;
  margin-top: 0;
  margin-right: auto;
  margin-bottom: 0;
  margin-left: 0px;
}
div#nav ul li{
  float:left;
  height:32px;
  overflow:hidden;
  background-image: url(images/YL30.jpg);
  background-repeat: repeat-y;
  background-position: right 0;
  padding-top: 0;
  padding-right: 1px;
  padding-bottom: 0;
  padding-left: 0px;
  font-family: Arial;
  font-size: 12px;
  line-height: 32px;
  font-weight: bold;
}
div#nav ul li a{
  float:left;
  height:100%;
  width: 77px;
  background:url(images/YL28.jpg) repeat-x;
  color:#fff;
  text-decoration:none;
  padding-top: 0;
  padding-right: 5px;
  padding-bottom: 0;
  padding-left: 5px;
  text-align:center;
}
div#nav ul li a.hover{
  clear:both;
  background-position:0 -32px;
  width: 77px;
}
div#nav ul li.on a{
  background-position:0 -32px;
}
div#nav ul li.nobg{background:none}
/* ]]> */
</style>
</head>
<body>
<div id="nav">
<ul class="clear">
<li><a href="#">本站</a></li>
<li><a href="#">网页特效</a></li>
<li><a href="#">工具软件</a></li>
<li><a href="#">脚本下载</a></li>
<li><a href="#">菜单导航</a></li>
<li><a href="#">层和布局</a></li>
<li><a href="#">论坛社区</a></li>
<li><a href="#">广告联系</a></li>
<li class="nobg"></li>
</ul>
</div>
<script type="text/javascript"> 
/* <![CDATA[ */
function nav(c, config){
  this.config = config || {speed: 10, num: 2};
  this.container = (typeof(c)=="object") ? c : document.getElementById(c);
  this.lineHeight = this.container.offsetHeight;
  this.scrollTimeId = null;
  var _this = this;  
  this.__construct = function (){
    var inner,el,href;
    inner = _this.container.childNodes[0].innerHTML;
    href = _this.container.childNodes[0].href;
    el = document.createElement("a");
    el.innerHTML = inner;
    el.href = href;
    el.className = 'hover';
    _this.container.appendChild(el);
    _this.container.onmouseover = function (){_this.start()};
    _this.container.onmouseout = function (){_this.end()};
  }();
  this.start = function (){
    _this.clear();
    _this.scrollTimeId = setTimeout(function(){_this.scrollUp();}, _this.config.speed);
  };
  this.end = function (){
    _this.clear();
    _this.scrollTimeId = setTimeout(function(){_this.scrollDown();}, _this.config.speed);
  };
  this.scrollUp = function (){
    var c = _this.container;  
    if(c.scrollTop >= _this.lineHeight){c.scrollTop = _this.lineHeight;return;}
    c.scrollTop += _this.config.num;
    _this.scrollTimeId = setTimeout(function(){_this.scrollUp();}, _this.config.speed);
  };
  this.scrollDown = function (){
    var c = _this.container;
    
    if(c.scrollTop <= 0){c.scrollTop = 0;return;}
    c.scrollTop -= _this.config.num;
    _this.scrollTimeId = setTimeout(function(){_this.scrollDown();}, _this.config.speed);
  };
  this.clear = function (){clearTimeout(_this.scrollTimeId)};
}
(function(){
  var container = document.getElementById('nav');
  var el_li = container.getElementsByTagName('li');
  var arr = [];
  for( var i = 0; i < el_li.length; i++){
    if(el_li[i].className == 'on') continue;
    arr[i] = new nav(el_li[i], {speed: 10, num: 4});
  }
})
();
/* ]]> */
</script>
</body>
</html>