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Alerts

Provide contextual feedback messages for typical user actions with the handful of available and flexible alert messages.

On this page

Examples

Alerts are available for any length of text, as well as an optional close button. For proper styling, use one of the four required contextual classes (e.g., .alert-success). For inline dismissal, use the alerts JavaScript plugin.

Boosted also adds a dedicated icon for each contextual class using .alert-icon, matching functional colors in palette:

  • success,
  • info,
  • warning,
  • danger.
html 
<div class="alert alert-success" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Success</span></span>
  <p>Success notification text goes here.</p>
</div>
<div class="alert alert-info" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Info</span></span>
  <p>Information notification text goes here.</p>
</div>
<div class="alert alert-warning" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Warning</span></span>
  <p>Warning notification text goes here.</p>
</div>
<div class="alert alert-danger" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Error</span></span>
  <p>Error notification text goes here.</p>
</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.

Live example

Click the button below to show an alert (hidden with inline styles to start), then dismiss (and destroy) it with the built-in close button.

html 
<div id="liveAlertPlaceholder"></div>
<button type="button" class="btn btn-primary" id="liveAlertBtn">Show live alert</button>

We use the following JavaScript to trigger our live alert demo:

const alertPlaceholder = document.getElementById('liveAlertPlaceholder')

const alert = (message, type, typeVisuallyHidden) => {
  const wrapper = document.createElement('div')
  wrapper.innerHTML = [
    `<div class="alert alert-${type} alert-dismissible" role="alert">`,
    '   <span class="alert-icon">',
    `      <span class="visually-hidden">${typeVisuallyHidden}</span>`,
    '   </span>',
    '   <p>',
    `     ${message}`,
    '   </p>',
    '   <button type="button" class="btn-close" data-bs-dismiss="alert">',
    '      <span class="visually-hidden">Close</span>',
    '   </button>',
    '</div>'
  ].join('')

  alertPlaceholder.append(wrapper)
}

const alertTrigger = document.getElementById('liveAlertBtn')
if (alertTrigger) {
  alertTrigger.addEventListener('click', () => {
    alert('Nice, you triggered this alert message!', 'success', 'Success')
  })
}

Sizes

Alerts come with a smaller variant: .alert-sm.

html 
<div class="alert alert-success alert-sm" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Success</span></span>
  <p>Success notification text goes here.</p>
</div>
<div class="alert alert-info alert-sm" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Info</span></span>
  <p>Information notification text goes here.</p>
</div>
<div class="alert alert-warning alert-sm" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Warning</span></span>
  <p>Warning notification text goes here.</p>
</div>
<div class="alert alert-danger alert-sm" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Error</span></span>
  <p>Error notification text goes here.</p>
</div>

Additional content

Alerts can also contain additional HTML elements like headings, links and paragraphs.

As of Boosted, it’s recommended to wrap your additional content in a <div> to ensure proper alignment and, for headings, to always use the .alert-heading class.

html 
<div class="alert alert-success" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Success</span></span>
  <div>
    <h4 class="alert-heading">Success notification text with <a href="#">a link</a> goes here.</h4>
    <p>Description text with <a href="#">a link</a> goes here.</p>
  </div>
</div>

Dismissing

Using the alert JavaScript plugin, it’s possible to dismiss any alert inline. Here’s how:

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

You can see this in action with a live demo:

html 
<div class="alert alert-warning alert-dismissible fade show" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Warning</span></span>
  <p>Warning notification text goes here.</p>
  <button type="button" class="btn-close" data-bs-dismiss="alert"><span class="visually-hidden">Close</span></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.bs.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.

Dark variant

Added in v5.2.0

Add .bg-dark to the .alert for a dark variant. Close button can be inverted as well by using the dark variant of close button

html 
<div class="alert alert-success bg-dark" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Success</span></span>
  <p>Success notification text goes here.</p>
</div>
<div class="alert alert-success bg-dark" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Success</span></span>
  <div>
    <h4 class="alert-heading">Success notification text with <a href="#">a link</a> goes here.</h4>
    <p>Description text with <a href="#">a link</a> goes here.</p>
  </div>
</div>
<div class="alert alert-warning alert-dismissible fade show bg-dark" role="alert">
  <span class="alert-icon"><span class="visually-hidden">Warning</span></span>
  <p>Warning notification text goes here.</p>
  <button type="button" class="btn-close btn-close-white" data-bs-dismiss="alert"><span class="visually-hidden">Close</span></button>
</div>

CSS

Variables

Added in v5.2.0

As part of Boosted’s evolving CSS variables approach, alerts now use local CSS variables on .alert for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.

  --#{$prefix}alert-bg: transparent;
  --#{$prefix}alert-padding-x: #{$alert-padding-x};
  --#{$prefix}alert-padding-y: #{$alert-padding-y};
  --#{$prefix}alert-margin-bottom: #{$alert-margin-bottom};
  @include rfs($font-size-base, --#{$prefix}alert-font-size); // Boosted mod
  --#{$prefix}alert-line-height: #{$line-height-base}; // Boosted mod
  --#{$prefix}alert-color: #{$alert-color}; // Boosted mod
  --#{$prefix}alert-border-color: transparent;
  --#{$prefix}alert-border: #{$alert-border-width} solid var(--#{$prefix}alert-border-color);
  --#{$prefix}alert-border-radius: #{$alert-border-radius};
  --#{$prefix}alert-logo-size: #{$alert-logo-size}; // Boosted mod
  --#{$prefix}alert-icon-size: #{$alert-icon-size}; // Boosted mod
  --#{$prefix}alert-icon-margin-y: #{$alert-icon-margin-y}; // Boosted mod
  --#{$prefix}alert-link-font-weight: #{$alert-link-font-weight}; // Boosted mod
  --#{$prefix}alert-heading-font-weight: #{$alert-heading-font-weight}; // Boosted mod
  --#{$prefix}alert-dismissible-padding-right: #{$alert-dismissible-padding-r}; // Boosted mod
  --#{$prefix}alert-btn-close-offset: #{$alert-btn-close-offset}; // Boosted mod

Customization through CSS variables can be seen on the .alert-sm class where we override specific values without adding duplicate CSS selectors.

  --#{$prefix}alert-padding-x: 0;
  --#{$prefix}alert-padding-y: #{$alert-padding-sm};
  --#{$prefix}alert-margin-bottom: 0;
  @include rfs($font-size-sm, --#{$prefix}alert-font-size);
  --#{$prefix}alert-line-height: #{$line-height-sm};
  --#{$prefix}alert-border: 0;
  --#{$prefix}alert-logo-size: #{$alert-logo-size-sm};
  --#{$prefix}alert-icon-size: #{$alert-icon-size-sm};
  --#{$prefix}alert-btn-close-offset: #{$alert-btn-close-offset-sm};

Sass variables 

$alert-padding-y:                   1rem;
$alert-padding-x:                   $spacer;
$alert-margin-bottom:               $spacer;
$alert-color:                       inherit; // Boosted mod
$alert-border-radius:               $border-radius;
$alert-link-font-weight:            null; // Boosted mod
$alert-heading-font-weight:         $font-weight-bold; // Boosted mod
$alert-border-width:                $border-width;

// Boosted mod
$alert-padding-sm:                  $spacer * .5;
$alert-icons: (
  "success": var(--#{$boosted-prefix}success-icon),
  "info":    escape-svg($info-icon),
  "warning": escape-svg($warning-icon),
  "danger":  var(--#{$boosted-prefix}error-icon)
);
$alert-logo-size:                   add($spacer * .5, 1rem);
$alert-logo-size-sm:                add(1rem, 1px);
$alert-icon-size:                   3rem;
$alert-icon-size-sm:                $alert-icon-size * .5;
$alert-icon-margin-y:               $spacer * .1;
$alert-btn-close-offset:            .5rem;
$alert-btn-close-offset-sm:         $spacer * .25;
// End mod

$alert-dismissible-padding-r:       $alert-padding-y * 3; // 3x covers width of x plus default padding on either side

Sass mixin

Used in combination with $theme-colors to create contextual modifier classes for our alerts.

@mixin alert-variant($background, $border, $color, $background-image) { // Boosted mod
  --#{$prefix}alert-color: #{$color};
  --#{$prefix}alert-bg: #{$background};
  --#{$prefix}alert-border: #{$border};

  // Boosted mod
  .alert-icon::before {
    background-image: $background-image;
  }
  // End mod

  // Boosted mod: no $enable-gradients test

  // Boosted mod: no .alert-link
}

Sass loop

Loop that generates the modifier classes with the alert-variant() mixin.

// Generate contextual modifier classes for colorizing the alert.

@each $state, $value in $alert-colors {
  $alert-background: transparent; // Boosted mod
  $alert-border: $alert-border-width solid $value; // Boosted mod
  // Boosted mod: no $alert-color change

  // Boosted mod: no contrast-ratio test
  .alert-#{$state} {
    @include alert-variant($alert-background, $alert-border, $alert-color, map-get($alert-icons, $state)); // Boosted mod
  }
}

JavaScript behavior

Initialize

Initialize elements as alerts

const alertList = document.querySelectorAll('.alert')
const alerts = [...alertList].map(element => new boosted.Alert(element))

For the sole purpose of dismissing an alert, it isn’t necessary to initialize the component manually via the JS API. By making use of data-bs-dismiss="alert", the component will be initialized automatically and properly dismissed.

See the triggers section for more details.

Triggers

Dismissal can be achieved with the data attribute on a button within the alert as demonstrated below:

<button type="button" class="btn-close" data-bs-dismiss="alert"><span class="visually-hidden">Close</span></button>

or on a button outside the alert using the data-bs-target as demonstrated below:

<button type="button" class="btn-close" data-bs-dismiss="alert" data-bs-target="#my-alert"><span class="visually-hidden">Close</span></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:

const bsAlert = new boosted.Alert('#myAlert')

This makes an alert listen for click events on descendant elements which have the data-bs-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. For example: boosted.Alert.getInstance(alert).
getOrCreateInstance Static method which returns an alert instance associated to a DOM element or create a new one in case it wasn’t initialized. You can use it like this: boosted.Alert.getOrCreateInstance(element).

Basic usage:

const alert = boosted.Alert.getOrCreateInstance('#myAlert')
alert.close()

Events

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

Event Description
close.bs.alert Fires immediately when the close instance method is called.
closed.bs.alert Fired when the alert has been closed and CSS transitions have completed. 
const myAlert = document.getElementById('myAlert')
myAlert.addEventListener('closed.bs.alert', event => {
  // 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()
})