jquery对象转化为DOM对象
<html>
<head>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<title></title>
<script src="http://code.jquery.com/jquery-1.11.3.js"></script>
</head>
<body>
<div>元素一</div>
<div>元素二</div>
<div>元素三</div>
<script type="text/javascript">
var $div = $('div'); //jQuery对象
//? div = ?
div.style.color = 'red'; //操作dom对象的属性
</script>
</body>
</html>