第一种： el.setAttribute('class','abc');
<!DOCTYPE HTML>
<HTML>
<HEAD>
<meta charset="utf-8" />
<title>setAttribute('class', 'abc')</title>
<style type="text/css">
.abc {
background: red;
}
</style>
</HEAD>
<BODY>
<div id="div">test div</div>
<script>
var div = document.getElementById('div');
div.setAttribute("class", "abc");
</script>
</BODY>
</HTML>
第二种： el.setAttribute('className', 'abc');
<!DOCTYPE HTML> <HTML> <HEAD> <meta charset="utf-8" /> <title>setAttribute('className', 'abc')</title> <style type="text/css"> .abc { background: red; } </style> </HEAD> <BODY> <div id="div">test div</div> <script> var div = document.getElementById('div'); div.setAttribute("className", "abc"); </script> </BODY> </HTML>
第三种：el.className = 'abc';
<!DOCTYPE HTML>
<HTML>
<HEAD>
<meta charset="utf-8" />
<title>el.className = 'abc'</title>
<style type="text/css">
.abc {
background: red;
}
</style>
</HEAD>
<BODY>
<div id="div">test div</div>
<script>
var div = document.getElementById('div');
div.className = 'abc';
</script>
</BODY>
</HTML>
建议使用第三种方法， 其他方法可能存在浏览器兼容问题。
原文：https://blog.csdn.net/yan791124465/article/details/71123664