警告框

为典型用户操作提供上下文反馈消息，并提供少量可用且灵活的警报消息。

在本页面

示例

警告可用于任何长度的文本，以及可选的关闭按钮。要获得正确的样式，请使用八个必需的上下文类之一（例如，.alert-success）。对于内联解除，请使用 alerts JavaScript 插件。

A simple primary alert—check it out!

A simple secondary alert—check it out!

A simple success alert—check it out!

A simple danger alert—check it out!

A simple warning alert—check it out!

A simple info alert—check it out!

A simple light alert—check it out!

A simple dark alert—check it out!

<div class="alert alert-primary" role="alert">
  A simple primary alert—check it out!
</div>
<div class="alert alert-secondary" role="alert">
  A simple secondary alert—check it out!
</div>
<div class="alert alert-success" role="alert">
  A simple success alert—check it out!
</div>
<div class="alert alert-danger" role="alert">
  A simple danger alert—check it out!
</div>
<div class="alert alert-warning" role="alert">
  A simple warning alert—check it out!
</div>
<div class="alert alert-info" role="alert">
  A simple info alert—check it out!
</div>
<div class="alert alert-light" role="alert">
  A simple light alert—check it out!
</div>
<div class="alert alert-dark" role="alert">
  A simple dark alert—check it out!
</div>

向辅助技术传达意义

使用颜色来增加意义只会提供一种视觉指示，而不会传达给辅助技术（如屏幕阅读器）的用户。确保由颜色表示的信息在内容本身（例如可见文本）中是明显的，或者通过其他方式包含，例如使用.visually-hidden 类隐藏的其他文本。

链接颜色

使用.alert-link实用程序类可以在任何警告中快速提供匹配的彩色链接。

A simple primary alert with an example link. Give it a click if you like.

A simple secondary alert with an example link. Give it a click if you like.

A simple success alert with an example link. Give it a click if you like.

A simple danger alert with an example link. Give it a click if you like.

A simple warning alert with an example link. Give it a click if you like.

A simple info alert with an example link. Give it a click if you like.

A simple light alert with an example link. Give it a click if you like.

A simple dark alert with an example link. Give it a click if you like.

<div class="alert alert-primary" role="alert">
  A simple primary alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-secondary" role="alert">
  A simple secondary alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-success" role="alert">
  A simple success alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-danger" role="alert">
  A simple danger alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-warning" role="alert">
  A simple warning alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-info" role="alert">
  A simple info alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-light" role="alert">
  A simple light alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>
<div class="alert alert-dark" role="alert">
  A simple dark alert with <a href="#" class="alert-link">an example link</a>. Give it a click if you like.
</div>

附加内容

警告还可以包含其他HTML元素，如标题、段落和分隔符。

Well done!

Aww yeah, you successfully read this important alert message. This example text is going to run a bit longer so that you can see how spacing within an alert works with this kind of content.

Whenever you need to, be sure to use margin utilities to keep things nice and tidy.

<div class="alert alert-success" role="alert">
  <h4 class="alert-heading">Well done!</h4>
  <p>Aww yeah, you successfully read this important alert message. This example text is going to run a bit longer so that you can see how spacing within an alert works with this kind of content.</p>
  <hr>
  <p class="mb-0">Whenever you need to, be sure to use margin utilities to keep things nice and tidy.</p>
</div>

解除

使用alert JavaScript插件，可以关闭任何内联警告。方法如下：

确保已加载警告插件或已编译的 Bootstrap JavaScript.
添加一个关闭按钮和. .alert-dismissible 类，该类在警告的右侧添加额外的填充，并定位关闭按钮。
在关闭按钮上，添加data-bs-dismiss="alert"属性，该属性触发JavaScript功能。一定要使用<button>元素在所有设备上进行正确的操作。
要在解除警告时设置警告动画，请确保添加 .fade 和 .show 类。

您可以在现场演示中看到这一点：

Holy guacamole! You should check in on some of those fields below.

<div class="alert alert-warning alert-dismissible fade show" role="alert">
  <strong>Holy guacamole!</strong> You should check in on some of those fields below.
  <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
</div>

当警告解除时，元素将从页面结构中完全移除。如果键盘用户使用“关闭”按钮解除警告，他们的焦点将突然丢失，并根据浏览器的不同，重置为页面/文档的开头。因此，我们建议包含额外的JavaScript来侦听closed.bs.alert事件并以编程方式将 focus() 设置到页面中最合适的位置。如果您计划将焦点移动到通常不接收焦点的非交互元素，请确保将tabindex="-1"添加到该元素。

JavaScript 行为

触发器

启用通过JavaScript取消警告：

var alertList = document.querySelectorAll('.alert')
alertList.forEach(function (alert) {
  new bootstrap.Alert(alert)
})

或者在警告中的按钮上显示data属性，如上所示：

<button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>

请注意，关闭警告会将其从DOM中删除。

方法

可以使用警告构造函数创建警告实例，例如：

var myAlert = document.getElementById('myAlert')
var bsAlert = new bootstrap.Alert(myAlert)

这使警告侦听具有 data-bs-dismiss="alert"属性的子元素上的单击事件。（当使用data-api的自动初始化时不需要。）

方法	描述
`close`	通过从DOM中删除警告来关闭警告。如果元素上存在`.fade` 和 `.show`类，则警告将在删除之前淡出。
`dispose`	摧毁元素的警告。（删除DOM元素上存储的数据）
`getInstance`	静态方法，它允许您获取与DOM元素关联的警告实例，您可以这样使用它： `bootstrap.Alert.getInstance(alert)`

var alertNode = document.querySelector('.alert')
var alert = bootstrap.Alert.getInstance(alertNode)
alert.close()

事件

Bootstrap的警告插件公开了一些事件，用于连接警告功能。

事件	描述
`close.bs.alert`	调用`close`实例方法时立即激发。
`closed.bs.alert`	在警告关闭且CSS转换完成时激发。

var myAlert = document.getElementById('myAlert')
myAlert.addEventListener('closed.bs.alert', function () {
  // do something, for instance, explicitly move focus to the most appropriate element,
  // so it doesn't get lost/reset to the start of the page
  // document.getElementById('...').focus()
})