E.C
匹配所有E元素中class名字等于C的元素集合。返回匹配集合
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function(){
$("div.test").addClass("test2");
});
</script>
<style>
.test{ border: 3px inset red; }
.test2{ border: 13px inset red; }
.test3{ border: 3px inset red; }
</style>
</head>
<body>
<div class="test"><p>Hello in a paragraph</p></div>
<div class="test3">Hello again! (with no paragraph)</div>
</body>
</html>
$("div.test").addClass("test2");
匹配div中class名字为test的div元素集合,以下为满足的元素集合(紫色)
<div class="test"><p>Hello in a paragraph</p></div>