<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>click事件</title>
<style type="text/css">
.box{
width: 200px;
height: 200px;
background-color: gold;
}
.sty{
background-color: green;
}
</style>
<script type="text/javascript" src="js/jquery-1.12.4.min.js"></script>
<script type="text/javascript">
$(function(){
$('#btn').click(function(){
$('.box').toggleClass('sty');
})
})
</script>
</head>
<body>
<input type="button" value="切换" id="btn">
<div class="box"></div>
</body>
</html>