类选择器(".class")
描述： 选择所有与给出类匹配的元素
对于类选择器来说，jquery使用的是javascript原生的方法getElementByClassName()
例子：
<!doctype html>
<html lang='zh'>
<head>
<meta charset="utf-8">
<title>class demo</title>
<style type="text/css">
div, span{
width: 120px;
height: 40px;
float: left;
padding: 10px;
margin: 10px;
background-color: #EEEEEE;
}
</style>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.9.1.js"></script>
</head>
<body>
<div class="notMe">div class="notMe"</div>
<div class="myClass">div class="myClass"</div>
<span class="myClass">span class="myClass"</span>
<script>
$(".myClass").css("border", "3px solid red");
</script>
</body>
</html>
例子：查找同时含有myclass 和 otherclass 类的元素。
<!doctype html>
<html lang="zh">
<head>
<meta charset='utf-8'>
<title>class demo</title>
<style type="text/css">
div,span{
width:120px;
height:40px;
padding:10px;
margin:10px;
background-color:#EEEEEE;
float: left;
}
</style>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.9.1.js"></script>
</head>
<body>
<div class="myclass">div class='myclass'</div>
<div class="myclass otherclass">div class="myclass otherclass"</div>
<span class="myclass otherclass">span class="myclass otherclass"</span>
<script type="text/javascript">
$(".myclass.otherclass").css("border", "13px solid red");
</script>
</body>
</html>
