弹出框控件和提示框有点类似，用户用鼠标点击元素后，就会显示。不过和提示框不同的是，弹出框能够显示的内容更多。
通过向元素添加 data-toggle="popover" 来来创建弹出框。
title 属性的内容为弹出框的标题，data-content 属性显示了弹出框的文本内容：
<a href="#" data-toggle="popover" title="弹出框标题" data-content="弹出框内容">多次点我</a>
注意: 弹出框要写在 jQuery 的初始化代码里: 然后在指定的元素上调用 popover() 方法。
以下实例可以在文档的任何地方使用弹出框：
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">
<h3>弹出框实例</h3>
<a href="#" data-toggle="popover" title="弹出框标题" data-content="弹出框内容">多次点我</a>
</div>
<script>
$(document).ready(function(){
$('[data-toggle="popover"]').popover();
});
</script>
</body>
</html>
默认情况下弹出框显示在元素右侧。
可以使用 data-placement 属性来设定弹出框显示的方向: 上：top, 下：bottom, 左：left 或 右：right:
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">
<h3>弹出框实例</h3> <br><br><br><br><br><br>
<a href="#" title="Header" data-toggle="popover" data-placement="top" data-content="Content">点我</a>
<a href="#" title="Header" data-toggle="popover" data-placement="bottom" data-content="Content">点我</a>
<a href="#" title="Header" data-toggle="popover" data-placement="left" data-content="Content">点我</a>
<a href="#" title="Header" data-toggle="popover" data-placement="right" data-content="Content">点我</a>
</div>
<script>
$(document).ready(function(){
$('[data-toggle="popover"]').popover();
});
</script>
</body>
</html>
默认情况下，弹出框在再次点击指定元素后就会关闭，你可以使用 data-trigger="focus" 属性来设置在鼠标点击元素外部区域来关闭弹出框：
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">
<h3>弹出框实例</h3> <br>
<a href="#" title="取消弹出框" data-toggle="popover" data-trigger="focus" data-content="点击文档的其他地方关闭我">点我</a>
</div>
<script>
$(document).ready(function(){
$('[data-toggle="popover"]').popover();
});
</script>
</body>
</html>
提示:如果你想实现在鼠标移动到元素上显示，移除后消失的效果，可以使用 data-trigger 属性，并设置值为 "hover":
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">
<h3>弹出框实例</h3> <br>
<a href="#" title="Header" data-toggle="popover" data-trigger="hover" data-content="一些内容">鼠标移动到我这</a>
</div>
<script>
$(document).ready(function(){
$('[data-toggle="popover"]').popover();
});
</script>
</body>
</html>