为什么在框里最上面会出现一条横线
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<title></title>
<style>
div {
width: 100px;
height: 90px;
float: left;
padding: 5px;
margin: 5px;
background-color: #EEEEEE;
}
</style>
<script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script>
</head>
<body>
<div class="aaron">
<p>class="aaron"</p>
<p>选中</p>
</div>
<div class="aaron">
<p>class="aaron"</p>
<p>选中</p>
</div>
<div class="imooc">
<p>class="imooc"</p>
<p>jQuery选中</p>
</div>
<div class="imooc">
<p>class="imooc"</p>
<p>jQuery选中</p>
</div>
<script type="text/javascript">
//获取页面中所有的元素
var elements1 = document.getElementsByTagName('*');
</script>
<script type="text/javascript">
//获取页面中所有的元素
var elements2 = $("*") ;
//原生与jQuery方法比较
//===表示数据和类型都相等
if(elements2.length === elements1.length){
elements2.css("border","1px solid red");
}
</script>
</body>
</html>
