切换不了效果。真的找不到问题在哪儿？？求教啊。
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<title>无标题文档</title>
<style type="text/css">
/* 制作静态网页的样式*/
*{margin:0px;padding:0px;}
body{font-size:14px;font-family:"微软雅黑";}
a{text-decoration:none;}
ul li{list-style:none;}
#box{border:1px solid #aaa;height:auto;margin:0 auto;
overflow:hidden;width:550px;
}
#box ul li{
height:auto;width:164px;border:1px solid #aaa;float:left;margin:7px;
}
.bottom{
background-color:#aaa;
height:40px;
line-height:40px;
text-align:center;
}
.top{height:40px;}
.top a{height:16px;width:16px;display:block;float:right;margin:5px;}
.btn-list-off{background:url("http://img1.sycdn.imooc.com//53ab7e86000153cc00710057.jpg") no-repeat -38px 0px;}
.btn-car-on{
background:url(" http://img1.sycdn.imooc.com//53ab7e86000153cc00710057.jpg") no-repeat -21px -34px;}
.btn-list-on{background:#fff url(http://img1.sycdn.imooc.com//53352d61000153cc00710057.jpg) no-repeat -21px 0px;}
.btn-car-off{background:#fff url(http://img1.sycdn.imooc.com//53352d61000153cc00710057.jpg) no-repeat -38px -32px;}
.a-img{height:164px;width:164px;display:block;overflow:hidden;}
p a,p span{
display:block;
line-height:23px;
padding-left:10px;
}
.small{height:50px;width:50px;float:left;margin:5px;}
</style>
<script type="text/javascript">
// 使用JS实现，点击不同的按钮(卡片模式和列表模式)显示不同的模式。
window.onload=function(){
//获取列表按钮的卡片按钮
var listBtn=document.getElementById("btn1");
var carBtn=document.getElementById("btn2");
//获取多个图片
var imgs=document.getElementsByTagName("img");
//列表模式
listBtn.onclick=function(){
//改变按钮的class
listBtn.className="btn-list-on";
carBtn.className="btn-car-off";
//改变图片路劲和父节点图片
for(var i=0;i<imgs.length;i++){
imgs[i].src=" http://img1.sycdn.imooc.com//53ab7cf4000196c000500050.jpg";
imgs[i].parentNode.className="a-img small";
}
}
//卡片模式
listBtn.onclick=function(){
//改变按钮的class
listBtn.className="btn-list-off";
carBtn.className="btn-car-on";
//改变图片路劲和父节点图片
for(var i=0;i<imgs.length;i++){
imgs[i].src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg";
imgs[i].parentNode.className="a-img";
}
}
}
</script>
</head>
<body>
<div id="box">
<div class="top">
<a href="#" title="列表模式" id="btn1" class="btn-list-off"></a>
<a href="#" title="卡片模式" id="btn2" class="btn-car-on"></a>
</div>
<ul>
<li>
<div class="con">
<a href="#" class="a-img ">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg" />
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li>
<li>
<div class="con">
<a href="#" class="a-img">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg"/>
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li><li>
<div class="con">
<a href="#" class="a-img">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg"/>
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li>
<li>
<div class="con">
<a href="#" class="a-img">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg"/>
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li><li>
<div class="con">
<a href="#" class="a-img">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg"/>
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li><li>
<div class="con">
<a href="#" class="a-img">
<img src="http://img1.sycdn.imooc.com//53ab7d16000159a801640236.jpg"/>
</a>
<p>
<a href="#">白阳</a>
<span>辽宁</span>
<span>21个共同好友</span>
</p>
</div>
<div class="bottom">
未分组的好友
</div>
</li>
</ul>
</div>
</body>
</html>
