本文概述
Boostrap警报用于提供创建预定义警报消息的简便方法。 Alert为你的消息添加了一种样式，以使其对用户更具吸引力。
<div>元素中使用了四个类来发出警报。
- .alert成功
- .alert-info
- 。警报警告
- .alert-danger
Boostrap警报示例
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Alerts</h2>
<div class="alert alert-success">
<strong>Success!</strong> This alert box indicates a successful or positive action.
</div>
<div class="alert alert-info">
<strong>Info!</strong> This alert box indicates a neutral informative change or action.
</div>
<div class="alert alert-warning">
<strong>Warning!</strong> This alert box indicates a warning that might need attention.
</div>
<div class="alert alert-danger">
<strong>Danger!</strong> This alert box indicates a dangerous or potentially negative action.
</div>
</div>
</body>
</html>Bootstrap4警报
Bootstrap 4在Bootstrap 3教程中定义的Bootstrap Alert中添加了4个新警报。
这些是：
- 主要：此警报框指示重要的操作。
- 次要的：此警报框指示次要的操作。
- 深：深灰色警报框。
- 浅：浅灰色警报框。
警报使用.alert类创建，然后使用上下文类之一创建。
所有上下文类别的列表：
- .alert成功
- .alert-info
- 。警报警告
- .alert-danger
- .alert-primary
- .alert-secondary
- .alert-light
- .alert-dark
例
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Alerts</h2>
<div class="alert alert-success">
<strong>Success!</strong> Used to indicate successful or positive action.
</div>
<div class="alert alert-info">
<strong>Info!</strong> Used to indicate a neutral informative change or action.
</div>
<div class="alert alert-warning">
<strong>Warning!</strong> Used to indicate a warning that might need attention.
</div>
<div class="alert alert-danger">
<strong>Danger!</strong> Used to indicate a dangerous or potentially negative action.
</div>
<div class="alert alert-primary">
<strong>Primary!</strong> Used to indicate an important action.
</div>
<div class="alert alert-secondary">
<strong>Secondary!</strong> Used to indicate a slightly less important action.
</div>
<div class="alert alert-dark">
<strong>Dark!</strong> Dark grey alert.
</div>
<div class="alert alert-light">
<strong>Light!</strong> Light grey alert.
</div>
</div>
</body>
</html>警报链接
你必须将alert-link类添加到警报框中的所有链接中，以创建“匹配的彩色链接”：
例：
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Bootstrap Alert Links</h2>
<div class="alert alert-success">
<strong>Success!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-info">
<strong>Info!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-warning">
<strong>Warning!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-danger">
<strong>Danger!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-primary">
<strong>Primary!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-secondary">
<strong>Secondary!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-dark">
<strong>Dark!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
<div class="alert alert-light">
<strong>Light!</strong> You should <a href="#" class="alert-link">read this message</a>.
</div>
</div>
</body>
</html>关闭警报
如果要关闭警报消息，则必须向警报容器添加.alert-dismissable类。然后将class =“ close”和data-dismiss =“ alert”添加到链接或按钮元素中（当你单击关闭符号时，警报框将关闭。）
例：
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Alerts</h2>
<div class="alert alert-success alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Success!</strong> This alert box could indicate a successful or positive action.
</div>
<div class="alert alert-info alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Info!</strong> This alert box could indicate a neutral informative change or action.
</div>
<div class="alert alert-warning alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Warning!</strong> This alert box could indicate a warning that might need attention.
</div>
<div class="alert alert-danger alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Danger!</strong> This alert box could indicate a dangerous or potentially negative action.
</div>
<div class="alert alert-primary alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Primary!</strong> Indicates an important action.
</div>
<div class="alert alert-secondary alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Secondary!</strong> Indicates a slightly less important action.
</div>
<div class="alert alert-dark alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Dark!</strong> Dark grey alert.
</div>
<div class="alert alert-light alert-dismissable">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Light!</strong> Light grey alert.
</div>
</div>
</body>
</html>动画警报
关闭警报消息时，可以使用.fade和.show类添加淡入淡出效果。
例：
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.6/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<h2>Animated Alerts Example</h2>
<div class="alert alert-success alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Success!</strong> This alert box could indicate a successful or positive action.
</div>
<div class="alert alert-info alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Info!</strong> This alert box could indicate a neutral informative change or action.
</div>
<div class="alert alert-warning alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Warning!</strong> This alert box could indicate a warning that might need attention.
</div>
<div class="alert alert-danger alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Danger!</strong> This alert box could indicate a dangerous or potentially negative action.
</div>
<div class="alert alert-primary alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Primary!</strong> Indicates an important action.
</div>
<div class="alert alert-secondary alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Secondary!</strong> Indicates a slightly less important action.
</div>
<div class="alert alert-dark alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Dark!</strong> Dark grey alert.
</div>
<div class="alert alert-light alert-dismissable fade show">
<button type="button" class="close" data-dismiss="alert">×</button>
<strong>Light!</strong> Light grey alert.
</div>
</div>
</body>
</html>
