帮忙改代码，看看哪里出错了，为什么到了嵌套的循环里面就获取不到索引了？？？
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>实践题 - 选项卡</title>
<style type="text/css">
/* CSS样式制作 */
* {
margin: 0;
padding: 0;
list-style: none;
font-size: 14px;
}
.div_body {
width: 497px;
height: 150px;
margin: 10px;
border: solid 1px #eee;
overflow: hidden;
}
.div_tit {
height: 27px;
position: relative;
}
.div_tit ul {
position: absolu te;
width: 501px;
left: -1px;
}
.div_tit li {
float: left;
width: 164px;
height: 26px;
line-height: 26px;
text-align: center;
overflow: hidden;
background-color: #f7f7f7;
border-bottom: 1px solid #eee;
padding: 0px 1px;
}
.div_tit li.select {
background-color: #fff;
border-bottom-color: #fff;
border-left: 1px solid #eee;
border-right: 1px solid #eee;
padding: 0;
font-weight: bolder;
}
.div_body li a:link,.div_body li a:visited {
text-decoration: none;
color: #000;
}
.div_body li a:hover {
color: #F90;
}
.div_con .div_mod {
margin: 15px 10px 10px 19px;
}
.div_con .div_mod ul li {
float: left;
width: 230px;
height: 25px;
overflow: hidden;
}
</style>
<script type="text/javascript">
// JS实现选项卡切换
window.onload = function() {
var dtit = document.getElementById("div_tit");
var tlists = dtit.getElementsByTagName("li");
//alert(tlists.length);
var dcon = document.getElementById("div_con");
var clists = dcon.getElementsByTagName("div");
//alert(clists.length);
for (var i = 0; i < tlists.length; i++) {
tlists[i].id = i;
tlists[i].onclick = function() {
//alert(this.id);
for (var j = 0; j < clists.length; j++) {
tlists[j].className = " ";
clists.style.display = "none";
}
//alert(this.id);//为什么这里不弹出？？？
this.className = "select";
clists[this.id].style.display = "block";
}
}
}
</script>
</head>
<body>
<!-- HTML页面布局 -->
<div id="div_body">
<div id="div_tit">
<ul>
<li><a href="#">房产</a>
</li>
<li><a href="#">家居</a>
</li>
<li><a href="#">二手房</a>
</li>
</ul>
</div>
<div id="div_con">
<div style="display:block">
<ul>
<li><span><a href="#">275万购昌平邻铁三居</a> </span></li>
<li><span><a href="#"> 总价20万买一居</a> </span></li>
<li><span><a href="#">200万内购五环三居</a> </span></li>
<li><span><a href="#">140万安家东三环</a> </span></li>
<li><span><a href="#">北京首现零首付楼盘</a> </span></li>
<li><span><a href="#">53万购东5环50平</a> </span></li>
<li><span><a href="#">京楼盘直降5000</a> </span></li>
<li><span><a href="#">中信府公园楼王现房</a> </span></li>
</ul>
</div>
<div style="display:none">
<ul>
<li><span><a href="#">40平出租屋大改造</a> </span></li>
<li><span><a href="#"> 美少女的混搭小窝</a> </span></li>
<li><span><a href="#"> 经典清新简欧爱家</a> </span></li>
<li><span><a href="#">90平老房焕发新生</a> </span></li>
<li><span><a href="#">新中式的酷色温情</a> </span></li>
<li><span><a href="#">66平撞色活泼家居</a> </span></li>
<li><span><a href="#">瓷砖就像选好老婆</a> </span></li>
<li><span><a href="#">卫生间烟道的设计</a> </span></li>
</ul>
</div>
<div style="display:none">
<ul>
<li><span><a href="#">通州豪华3居260万</a> </span></li>
<li><span><a href="#">二环稀缺2居250w甩</a> </span></li>
<li><span><a href="#">西3环通透2居290万</a> </span></li>
<li><span><a href="#">130万2居限量抢购</a> </span></li>
<li><span><a href="#"> 黄城根小学学区仅260万</a> </span></li>
<li><span><a href="#">121平70万抛!</a> </span></li>
<li><span><a href="#">独家别墅280万 </a> </span></li>
<li><span><a href="#">苏州桥2居优惠价248万</a> </span></li>
</ul>
</div>
</div>
</div>
</body>
</html>
