<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
*{
margin:0;
padding:0;
}
div {
width: 400px;
height:400px;
background-color:pink;
}
</style>
</head>
<body>
<div></div>
<script>
var div = document.querySelector('div');
div.onclick = function() {
this.style.width = '200px';
this.style.height = '200px';
this.style.backgroundColor = 'green';
}
</script>
</body>
</html>
在里面定义一个变量 var flag = 0; 使用if ....else.... 循环可以吗
