徽章（Badges）功能的用途主要是用来突显新的或者未读的项，让该项更加显眼。徽章的使用其实很简单，只需要将 .badge 类加上带有指定意义的颜色类 (如 .badge-secondary) 添加到 <span> 元素上即可。
注： 徽章可以根据父元素的大小的变化而变化:
实例：
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap4 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" >
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/popper.js/1.12.5/umd/popper.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/bootstrap/4.1.0/js/bootstrap.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>徽章</h2>
<h1>测试标题 <span class="badge badge-secondary">New</span></h1>
<h2>测试标题 <span class="badge badge-secondary">New</span></h2>
<h3>测试标题 <span class="badge badge-secondary">New</span></h3>
<h4>测试标题 <span class="badge badge-secondary">New</span></h4>
<h5>测试标题 <span class="badge badge-secondary">New</span></h5>
<h6>测试标题 <span class="badge badge-secondary">New</span></h6>
</div>
</body>
</html>
各种颜色类型的徽章
以下列出了所有颜色类型的徽章:
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap4 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" >
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/popper.js/1.12.5/umd/popper.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/bootstrap/4.1.0/js/bootstrap.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>各种颜色类型的徽章</h2>
<span class="badge badge-primary">主要</span>
<span class="badge badge-secondary">次要</span>
<span class="badge badge-success">成功</span>
<span class="badge badge-danger">危险</span>
<span class="badge badge-warning">警告</span>
<span class="badge badge-info">信息</span>
<span class="badge badge-light">浅色</span>
<span class="badge badge-dark">深色</span>
</div>
</body>
</html>
药丸形状徽章
使用 .badge-pill 类来设置药丸形状徽章:
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap4 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" >
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/popper.js/1.12.5/umd/popper.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/bootstrap/4.1.0/js/bootstrap.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>药丸形状徽章</h2>
<span class="badge badge-pill badge-default">默认</span>
<span class="badge badge-pill badge-primary">主要</span>
<span class="badge badge-pill badge-success">成功</span>
<span class="badge badge-pill badge-info">信息</span>
<span class="badge badge-pill badge-warning">警告</span>
<span class="badge badge-pill badge-danger">危险</span>
</div>
</body>
</html>
徽章插入到元素内
以下实例将徽章嵌入到按钮内：
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap4 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdn.bootcss.com/bootstrap/4.1.0/css/bootstrap.min.css" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" rel="external nofollow" target="_blank" >
<script src="https://cdn.bootcss.com/jquery/3.2.1/jquery.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/popper.js/1.12.5/umd/popper.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
<script src="https://cdn.bootcss.com/bootstrap/4.1.0/js/bootstrap.min.js" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>徽章嵌入到按钮内</h2>
<button type="button" class="btn btn-primary">
Messages <span class="badge badge-light">4</span>
</button>
<button type="button" class="btn btn-danger">
Notifications <span class="badge badge-light">7</span>
</button>
</div>
</body>
</html>