//通过class属性值匹配元素
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>.class选择器</title>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
<style type="text/css">
.class1{color:red;}
</style>
<script type="text/javascript" src="jquery-1.7.1.min.js"></script>
<script type="text/javascript">
window.onload=function(){
document.getElementById('btnOk').onclick=function(){
$(' .class1 ').html('php'); //把使用.class1的元素匹配并内容替换
};
};
</script>
</head>
<body>
<div id="div1">div1</div>
<hr/>
<div class="class1">div2</div>
<hr/>
<p class="class1">杨</p>
<input type="button" id='btnOk' value='确定' />
</body>
</html>