<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>className属性</title>
<style type="text/css">
.myDiv{
height: 50px;
width: 50px;
border: 1px solid red;
}
.newStyle{
height: 150px;
width: 150px;
border: 2px solid pink;
}
</style>
</head>
<body>
<div class="myDiv" id="myDiv"></div>
<script type="text/javascript">
var div= document.getElementById("myDiv");
div.onclick=function(){
div.className="newStyle"; //newStyle是我们需要设置class的名称
}
</script>
</body>
</html>
原文：http://www.cnblogs.com/zwy0709/p/7774972.html