示例代码：
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<meta name="Generator" content="EditPlus®">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<link rel="stylesheet"type="text/css"href="mystyle.css">
<title>Document</title>
<style type="text/css">
ul{counter-reset:num;}
li:after{content:counter(num);counter-increment:num;}
</style>
</head>
<body>
<h2>自增值id或序号</h2>
<ul>
<li>data-index=</li>
<li>data-index=</li>
<li>data-index=</li>
<li>data-index=</li>
<li>data-index=</li>
<li>data-index=</li>
<li>data-index=</li>
</ul>
</body>
</html>