进度条可以明确显示用户任务的完成进度，是日常使用频率非常高的一项功能。在Bootstrap4中，进度条的创建也是相对比较简单的。
进度条创建步骤：
1、添加一个带有 .progress 类的 <div>。
2、接着，在上面的 <div> 内，添加一个带有 class .progress-bar 的空的 <div>。
3、添加一个带有百分比表示的宽度的 style 属性，例如 表示进度条在 70% 的位置。
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>基本进度条</h2>
<p>要创建一个默认的进度条，可以在容器元素上添加 .progress 类，在子元素上添加 progress-bar 类，并设置进度条进度情况：:</p>
<div class="progress">
<div class="progress-bar" style="width:70%"></div>
</div>
</div>
</body>
</html>
进度条高度
进度条高度默认为 16px，不过我们可以使用 CSS 的 height 属性来对高度进行修改：
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>进度条高度</h2>
<p>进度条高度默认为 16px。我们可以使用 CSS 的 height 属性来修改他：</p>
<div class="progress" style="height:10px">
<div class="progress-bar" style="width:40%"></div>
</div>
</br>
<div class="progress" style="height:20px">
<div class="progress-bar" style="width:50%"></div>
</div>
</br>
<div class="progress"style="height:30px">
<div class="progress-bar" style="width:60%"></div>
</div>
</div>
</body>
</html>
进度条宽度应设置在progress上才能生效，progress-bar默认继承progress的宽度。
进度条标签
可以在进度条内添加文本，如进度的百分比，这样可以让用户一眼就看出当前任务的进度：
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>进度条文本标签</h2>
<div class="progress">
<div class="progress-bar" style="width:70%">70%</div>
</div>
</div>
</body>
</html>
进度条颜色
进度条默认是蓝色，不过我们可以通过添加颜色类来对进度条的颜色进行修改。
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>多种颜色的进度条</h2>
<p>Bootstrap4 提供了以下几种进度条颜色:</p>
<div class="progress">
<div class="progress-bar" style="width:30%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-success" style="width:40%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-info" style="width:50%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-warning" style="width:60%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-danger" style="width:70%"></div>
</div>
</div>
</body>
</html>
条纹的进度条
可以使用 .progress-bar-striped 类来改变进度条的样式，将其设置为条纹进度条。
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>条纹的进度条</h2>
<p>可以使用 .progress-bar-striped 类来设置条纹进度条：</p>
<div class="progress">
<div class="progress-bar progress-bar-striped" style="width:30%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-success progress-bar-striped" style="width:40%"></div>
</div>
<br>
<div class="progress">
<div class="progress-bar bg-info progress-bar-striped" style="width:50%"></div>
</div>
</div>
</body>
</html>
进度条动画
使用 .progress-bar-animated 类可以为进度条添加动画：
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>动画进度条</h2>
<p>使用 .progress-bar-animated 类可以为进度条添加动画：</p>
<div class="progress">
<div class="progress-bar progress-bar-striped progress-bar-animated" style="width:40%"></div>
</div>
</div>
</body>
</html>
混合色彩进度条
单个进度条可以设置成多种颜色：
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" 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" 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" 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" rel="external nofollow" rel="external nofollow" rel="external nofollow" ></script>
</head>
<body>
<div class="container">
<h2>混合色彩进度条</h2>
<p>进度条可以设置多种颜色:</p>
<div class="progress">
<div class="progress-bar bg-success" style="width:40%">
Free Space
</div>
<div class="progress-bar bg-warning" style="width:10%">
Warning
</div>
<div class="progress-bar bg-danger" style="width:20%">
Danger
</div>
</div>
</div>
</body>
</html>