设置样式
var div = document.querySelector("div");
// 标签.style.css属性 = 值
div.style.width = '200px';
div.style.height = '200px';
div.style["background-color"] = 'red'; //因为有斜杠可以用中括号代替.或者用驼峰,如下
div.style.border = '5px solid #000';
div.style.borderColor = '#0f0';
类名操作
<!Doctype html>
<html>
<head>
<meta charset='UTF-8'>
<title>Document</title>
<style>
.fl{
float:left;
}
.clearfix:after{
content:'';
display:block;
clear:both;
}
.box{
width: 100px;
height: 100px;
background-color: #f00;
}
.hezi{
border:20px solid #0f0;
}
.m{
margin:50px;
}
</style>
</head>
<body>
<div></div>
</body>
<script>
var div = document.querySelector("div");
// 类名操作 - 标签.className
div.className = 'box';
div.className = 'box hezi';
div.className = '';
div.className = 'box m';
console.log(div.className);
</script>
</html>