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Bootstrap alerts

Bootstrap alerts give contextual feedback information for common user operations. The alert component is delivered with a bunch of usable and adjustable alert messages.

Examples

Bootstrap alert is prepared for any length of text, as well as an optional close button. For a styling, use one of the required contextual classes (e.g., .alert-success). For inline dismissal, use the alerts JavaScript plugin.

<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>
Conveying meaning to assistive technologies

Using color to add meaning only provides a visual indication, which will not be conveyed to users of assistive technologies – such as screen readers. Ensure that information denoted by the color is either obvious from the content itself (e.g. the visible text), or is included through alternative means, such as additional text hidden with the .visually-hidden class.

Use the .alert-link utility class to immediately give matching colored links inside any alert.

<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>

Additional content

Alert can also incorporate supplementary HTML elements like heading, paragraph, and divider.

<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>

Dismissing

Using the JavaScript plugin, it’s possible to remove any alert.

  • Be sure you’ve loaded the bootstrap alert plugin or the compiled CoreUI JavaScript.
  • Add a close button and the .alert-dismissible class, which adds some extra padding to the right of the alert component and positions the .close button.
  • On the close button, add the data-coreui-dismiss="alert" attribute, which triggers the JavaScript functionality. You have to use the <button> element with it for proper behavior across all devices.
  • To animate alerts when dismissing them, you have to add the .fade and .show classes.

You can see this in action with a live demo:

<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-coreui-dismiss="alert" aria-label="Close"></button>
</div>
When an alert is dismissed, the element is completely removed from the page structure. If a keyboard user dismisses the alert using the close button, their focus will suddenly be lost and, depending on the browser, reset to the start of the page/document. For this reason, we recommend including additional JavaScript that listens for the closed.coreui.alert event and programmatically sets focus() to the most appropriate location in the page. If you’re planning to move focus to a non-interactive element that normally does not receive focus, make sure to add tabindex="-1" to the element.

JavaScript behavior

Triggers

Enable dismissal of an alert via JavaScript:

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

Or with data attributes on a button within the alert, as demonstrated above:

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

Note that closing an alert will remove it from the DOM.

Methods

You can create an alert instance with the alert constructor, for example:

var myAlert = document.getElementById('myAlert')
var cuiAlert = new coreui.Alert(myAlert)

This makes an alert listen for click events on descendant elements which have the data-coreui-dismiss="alert" attribute. (Not necessary when using the data-api’s auto-initialization.)

Method Description
close Closes an alert by removing it from the DOM. If the .fade and .show classes are present on the element, the alert will fade out before it is removed.
dispose Destroys an element's alert. (Removes stored data on the DOM element)
getInstance Static method which allows you to get the alert instance associated to a DOM element, you can use it like this: coreui.Alert.getInstance(alert)
var alertNode = document.querySelector('.alert')
var alert = coreui.Alert.getInstance(alertNode)
alert.close()

Events

Bootstrap’s alert plugin exposes a few events for hooking into alert functionality.

Event Description
close.coreui.alert Fires immediately when the close instance method is called.
closed.coreui.alert Fired when the alert has been closed and CSS transitions have completed.
var myAlert = document.getElementById('myAlert')
myAlert.addEventListener('closed.coreui.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()
})

Customizing

SASS

Variables

$alert-padding-y:               $spacer;
$alert-padding-x:               $spacer;
$alert-margin-bottom:           1rem;
$alert-border-radius:           $border-radius;
$alert-link-font-weight:        $font-weight-bold;
$alert-border-width:            $border-width;
$alert-bg-scale:                -80%;
$alert-border-scale:            -70%;
$alert-color-scale:             40%;
$alert-dismissible-padding-r:   $alert-padding-x * 3; // 3x covers width of x plus default padding on either side


$alert-variants: (
  "primary": alert-color-map($primary),
  "secondary": alert-color-map($secondary),
  "success": alert-color-map($success),
  "danger": alert-color-map($danger),
  "warning": alert-color-map($warning),
  "info": alert-color-map($info),
  "light": alert-color-map($light),
  "dark": alert-color-map($dark)
);

Variants

CoreUI allows defining variant colors in two ways.

Check out our Sass maps and loops docs for how to customize these loops and extend CoreUI’s base-modifier approach to your own code.

Manual

You can define each color manually and keep full control of the component appearance.

$alert-variants: (
  "primary": (
    "background": $your-bg-color,
    "border": $your-border-color,
    "color": $your-color,
    "link-color": $your-link-color
  )
  ...
);
Color function

The color set can be generated automatically thanks to our alert-color-map function.

@function alert-color-map($color) {
  @return (
    "background": shift-color($color, $alert-bg-scale),
    "border": shift-color($color, $alert-border-scale),
    "color": shift-color($color, $alert-color-scale),
    "link-color": shade-color(shift-color($color, $alert-color-scale), 20%)
  );
}
$alert-variants: (
  "primary": alert-color-map($primary),
  ...
);

Modifiers

CoreUI’s alert component is built with a base-modifier class approach. This means the bulk of the styling is contained to a base class .alert while style variations are confined to modifier classes (e.g., .alert-danger). These modifier classes are built from the $alert-variants map to make customizing the number and name of our modifier classes.

// Generate contextual modifier classes for colorizing the alert.

@each $state, $map in $alert-variants {
  $background: var(--#{$variable-prefix}alert-bg, map-get($map, "background"));
  $border: var(--#{$variable-prefix}alert-border-color, map-get($map, "border"));
  $color: var(--#{$variable-prefix}alert-color, contrast-ratio-correction(map-get($map, "color"), map-get($map, "background"), abs($alert-color-scale), $state));
  $link-color: var(--#{$variable-prefix}alert-link-color, map-get($map, "link-color"));

  .alert-#{$state} {
    @include alert-variant($background, $border, $color, $link-color);
  }
}

CSS Vars

--cui-alert-bg
--cui-alert-border-color
--cui-alert-color
--cui-alert-link-color