List group
List groups are a flexible and powerful component for displaying a series of content. Modify and extend them to support just about any content within.
Basic example
The most basic list group is an unordered list with list items and the proper classes. Build upon it with the options that follow, or with your own CSS as needed.
- An item
- A second item
- A third item
- A fourth item
- And a fifth one
<ul class="list-group">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
<li class="list-group-item">A fourth item</li>
<li class="list-group-item">And a fifth one</li>
</ul>
Active items
Add .active
to a .list-group-item
to indicate the current active selection.
- An active item
- A second item
- A third item
- A fourth item
- And a fifth one
<ul class="list-group">
<li class="list-group-item active" aria-current="true">An active item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
<li class="list-group-item">A fourth item</li>
<li class="list-group-item">And a fifth one</li>
</ul>
Disabled items
Add .disabled
to a .list-group-item
to make it appear disabled. Note that some elements with .disabled
will also require custom JavaScript to fully disable their click events (e.g., links).
- A disabled item
- A second item
- A third item
- A fourth item
- And a fifth one
<ul class="list-group">
<li class="list-group-item disabled" aria-disabled="true">A disabled item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
<li class="list-group-item">A fourth item</li>
<li class="list-group-item">And a fifth one</li>
</ul>
Links and buttons
Use <a>
s or <button>
s to create actionable list group items with hover, disabled, and active states by adding .list-group-item-action
. We separate these pseudo-classes to ensure list groups made of non-interactive elements (like <li>
s or <div>
s) don’t provide a click or tap affordance.
Be sure to not use the standard .btn
classes here.
<div class="list-group">
<a href="#" class="list-group-item list-group-item-action active" aria-current="true">
The current link item
</a>
<a href="#" class="list-group-item list-group-item-action">A second link item</a>
<a href="#" class="list-group-item list-group-item-action">A third link item</a>
<a href="#" class="list-group-item list-group-item-action">A fourth link item</a>
<a class="list-group-item list-group-item-action disabled" aria-disabled="true">A disabled link item</a>
</div>
With <button>
s, you can also make use of the disabled
attribute instead of the .disabled
class. Sadly, <a>
s don’t support the disabled attribute.
<div class="list-group">
<button type="button" class="list-group-item list-group-item-action active" aria-current="true">
The current button
</button>
<button type="button" class="list-group-item list-group-item-action">A second button item</button>
<button type="button" class="list-group-item list-group-item-action">A third button item</button>
<button type="button" class="list-group-item list-group-item-action">A fourth button item</button>
<button type="button" class="list-group-item list-group-item-action" disabled>A disabled button item</button>
</div>
Flush
Add .list-group-flush
to remove some borders and rounded corners to render list group items edge-to-edge in a parent container (e.g., cards).
- An item
- A second item
- A third item
- A fourth item
- And a fifth one
<ul class="list-group list-group-flush">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
<li class="list-group-item">A fourth item</li>
<li class="list-group-item">And a fifth one</li>
</ul>
Numbered
Add the .list-group-numbered
modifier class (and optionally use an <ol>
element) to opt into numbered list group items. Numbers are generated via CSS (as opposed to a <ol>
s default browser styling) for better placement inside list group items and to allow for better customization.
Numbers are generated by counter-reset
on the <ol>
, and then styled and placed with a ::before
pseudo-element on the <li>
with counter-increment
and content
.
- A list item
- A list item
- A list item
<ol class="list-group list-group-numbered">
<li class="list-group-item">A list item</li>
<li class="list-group-item">A list item</li>
<li class="list-group-item">A list item</li>
</ol>
These work great with custom content as well.
-
SubheadingContent for list item
-
SubheadingContent for list item
-
SubheadingContent for list item
<ol class="list-group list-group-numbered">
<li class="list-group-item d-flex justify-content-between align-items-start">
<div class="ms-2 me-auto">
<div class="fw-bold">Subheading</div>
Content for list item
</div>
<span class="badge bg-primary rounded-pill">14</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-start">
<div class="ms-2 me-auto">
<div class="fw-bold">Subheading</div>
Content for list item
</div>
<span class="badge bg-primary rounded-pill">14</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-start">
<div class="ms-2 me-auto">
<div class="fw-bold">Subheading</div>
Content for list item
</div>
<span class="badge bg-primary rounded-pill">14</span>
</li>
</ol>
Horizontal
Add .list-group-horizontal
to change the layout of list group items from vertical to horizontal across all breakpoints. Alternatively, choose a responsive variant .list-group-horizontal-{sm|md|lg|xl|xxl}
to make a list group horizontal starting at that breakpoint’s min-width
. Currently horizontal list groups cannot be combined with flush list groups.
ProTip: Want equal-width list group items when horizontal? Add .flex-fill
to each list group item.
- An item
- A second item
- A third item
- An item
- A second item
- A third item
- An item
- A second item
- A third item
- An item
- A second item
- A third item
- An item
- A second item
- A third item
- An item
- A second item
- A third item
<ul class="list-group list-group-horizontal">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
<ul class="list-group list-group-horizontal-sm">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
<ul class="list-group list-group-horizontal-md">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
<ul class="list-group list-group-horizontal-lg">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
<ul class="list-group list-group-horizontal-xl">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
<ul class="list-group list-group-horizontal-xxl">
<li class="list-group-item">An item</li>
<li class="list-group-item">A second item</li>
<li class="list-group-item">A third item</li>
</ul>
Contextual classes
Use contextual classes to style list items with a stateful background and color.
- A simple default list group item
- A simple primary list group item
- A simple secondary list group item
- A simple success list group item
- A simple danger list group item
- A simple warning list group item
- A simple info list group item
- A simple light list group item
- A simple dark list group item
<ul class="list-group">
<li class="list-group-item">A simple default list group item</li>
<li class="list-group-item list-group-item-primary">A simple primary list group item</li>
<li class="list-group-item list-group-item-secondary">A simple secondary list group item</li>
<li class="list-group-item list-group-item-success">A simple success list group item</li>
<li class="list-group-item list-group-item-danger">A simple danger list group item</li>
<li class="list-group-item list-group-item-warning">A simple warning list group item</li>
<li class="list-group-item list-group-item-info">A simple info list group item</li>
<li class="list-group-item list-group-item-light">A simple light list group item</li>
<li class="list-group-item list-group-item-dark">A simple dark list group item</li>
</ul>
Contextual classes also work with .list-group-item-action
. Note the addition of the hover styles here not present in the previous example. Also supported is the .active
state; apply it to indicate an active selection on a contextual list group item.
<div class="list-group">
<a href="#" class="list-group-item list-group-item-action">A simple default list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-primary">A simple primary list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-secondary">A simple secondary list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-success">A simple success list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-danger">A simple danger list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-warning">A simple warning list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-info">A simple info list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-light">A simple light list group item</a>
<a href="#" class="list-group-item list-group-item-action list-group-item-dark">A simple dark list group item</a>
</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.
With badges
Add badges to any list group item to show unread counts, activity, and more with the help of some utilities.
- A list item 14
- A second list item 2
- A third list item 1
<ul class="list-group">
<li class="list-group-item d-flex justify-content-between align-items-center">
A list item
<span class="badge bg-primary rounded-pill">14</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-center">
A second list item
<span class="badge bg-primary rounded-pill">2</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-center">
A third list item
<span class="badge bg-primary rounded-pill">1</span>
</li>
</ul>
Custom content
Add nearly any HTML within, even for linked list groups like the one below, with the help of flexbox utilities.
List group item heading
3 days agoSome placeholder content in a paragraph.
And some small print.List group item heading
3 days agoSome placeholder content in a paragraph.
And some muted small print.List group item heading
3 days agoSome placeholder content in a paragraph.
And some muted small print.<div class="list-group">
<a href="#" class="list-group-item list-group-item-action active" aria-current="true">
<div class="d-flex w-100 justify-content-between">
<h5 class="mb-1">List group item heading</h5>
<small>3 days ago</small>
</div>
<p class="mb-1">Some placeholder content in a paragraph.</p>
<small>And some small print.</small>
</a>
<a href="#" class="list-group-item list-group-item-action">
<div class="d-flex w-100 justify-content-between">
<h5 class="mb-1">List group item heading</h5>
<small class="text-muted">3 days ago</small>
</div>
<p class="mb-1">Some placeholder content in a paragraph.</p>
<small class="text-muted">And some muted small print.</small>
</a>
<a href="#" class="list-group-item list-group-item-action">
<div class="d-flex w-100 justify-content-between">
<h5 class="mb-1">List group item heading</h5>
<small class="text-muted">3 days ago</small>
</div>
<p class="mb-1">Some placeholder content in a paragraph.</p>
<small class="text-muted">And some muted small print.</small>
</a>
</div>
Checkboxes and radios
Place Boosted Innovation Cup’s checkboxes and radios within list group items and customize as needed. You can use them without <label>
s, but please remember to include an aria-label
attribute and value for accessibility.
<ul class="list-group">
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="firstCheckbox">
<label class="form-check-label" for="firstCheckbox">First checkbox</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="secondCheckbox">
<label class="form-check-label" for="secondCheckbox">Second checkbox</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="thirdCheckbox">
<label class="form-check-label" for="thirdCheckbox">Third checkbox</label>
</li>
</ul>
<ul class="list-group">
<li class="list-group-item">
<input class="form-check-input me-1" type="radio" name="listGroupRadio" value="" id="firstRadio" checked>
<label class="form-check-label" for="firstRadio">First radio</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="radio" name="listGroupRadio" value="" id="secondRadio">
<label class="form-check-label" for="secondRadio">Second radio</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="radio" name="listGroupRadio" value="" id="thirdRadio">
<label class="form-check-label" for="thirdRadio">Third radio</label>
</li>
</ul>
You can use .stretched-link
on <label>
s to make the whole list group item clickable.
<ul class="list-group">
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="firstCheckboxStretched">
<label class="form-check-label stretched-link" for="firstCheckboxStretched">First checkbox</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="secondCheckboxStretched">
<label class="form-check-label stretched-link" for="secondCheckboxStretched">Second checkbox</label>
</li>
<li class="list-group-item">
<input class="form-check-input me-1" type="checkbox" value="" id="thirdCheckboxStretched">
<label class="form-check-label stretched-link" for="thirdCheckboxStretched">Third checkbox</label>
</li>
</ul>
Dark variant
Add .list-group-dark
to the .list-group
for a dark variant.
- A simple default list group item
- A simple active list group item
- A simple disabled list group item
<ul class="list-group list-group-dark">
<li class="list-group-item">A simple default list group item</li>
<li class="list-group-item active">A simple active list group item</li>
<li class="list-group-item disabled" aria-disabled="true">A simple disabled list group item</li>
</ul>
Dark variant also work with .list-group-item-action
.
<div class="list-group list-group-dark">
<a class="list-group-item list-group-item-action" href="#">A simple default link list group item</a>
<a class="list-group-item list-group-item-action active" href="#">A simple active link list group item</a>
<a class="list-group-item list-group-item-action disabled" aria-disabled="true">A simple disabled link list group item</a>
</div>
CSS
Variables
As part of Boosted Innovation Cup’s evolving CSS variables approach, list groups now use local CSS variables on .list-group
for enhanced real-time customization. Values for the CSS variables are set via Sass, so Sass customization is still supported, too.
--#{$prefix}list-group-color: #{$list-group-color};
--#{$prefix}list-group-bg: #{$list-group-bg};
--#{$prefix}list-group-border-color: #{$list-group-border-color};
--#{$prefix}list-group-border-width: #{$list-group-border-width};
--#{$prefix}list-group-border-radius: #{$list-group-border-radius};
--#{$prefix}list-group-item-padding-x: #{$list-group-item-padding-x};
--#{$prefix}list-group-item-padding-y: #{$list-group-item-padding-y};
--#{$prefix}list-group-action-color: #{$list-group-action-color};
--#{$prefix}list-group-action-hover-color: #{$list-group-action-hover-color};
// Boosted mod: no --#{$prefix}list-group-action-hover-bg
--#{$prefix}list-group-action-active-color: #{$list-group-action-active-color};
--#{$prefix}list-group-action-active-bg: #{$list-group-action-active-bg};
--#{$prefix}list-group-disabled-color: #{$list-group-disabled-color};
--#{$prefix}list-group-disabled-bg: #{$list-group-disabled-bg};
--#{$prefix}list-group-active-color: #{$list-group-active-color};
--#{$prefix}list-group-active-bg: #{$list-group-active-bg};
--#{$prefix}list-group-active-border-color: #{$list-group-active-border-color};
Customization through CSS variables can be seen on the .list-group-dark
modifier class where we override specific values without adding duplicate CSS selectors.
--#{$prefix}list-group-color: #{$list-group-dark-color}; // Boosted mod
--#{$prefix}list-group-bg: #{$list-group-dark-bg}; // Boosted mod
--#{$prefix}list-group-border-color: #{$list-group-dark-border-color}; // Boosted mod
--#{$prefix}list-group-action-color: #{$list-group-dark-action-color}; // Boosted mod
--#{$prefix}list-group-action-hover-color: #{$list-group-dark-action-hover-color}; // Boosted mod
--#{$prefix}list-group-action-active-color: #{$list-group-dark-action-active-color}; // Boosted mod
--#{$prefix}list-group-action-active-bg: #{$list-group-dark-action-active-bg}; // Boosted mod
--#{$prefix}list-group-disabled-color: #{$list-group-dark-disabled-color}; // Boosted mod
--#{$prefix}list-group-disabled-bg: #{$list-group-dark-disabled-bg}; // Boosted mod
--#{$prefix}list-group-active-color: #{$list-group-dark-active-color}; // Boosted mod
--#{$prefix}list-group-active-bg: #{$list-group-dark-active-bg}; // Boosted mod
--#{$prefix}list-group-active-border-color: #{$list-group-dark-active-border-color}; // Boosted mod
Sass variables
Variables for all list groups:
$list-group-color: $black; // Boosted mod
$list-group-bg: $white;
$list-group-border-color: $gray-500; // Boosted mod
$list-group-border-width: $border-width;
$list-group-border-radius: $border-radius;
$list-group-item-padding-y: .875rem; // Boosted mod
$list-group-item-padding-x: $spacer; // Boosted mod
// Boosted mod: no $list-group-item-bg-scale
// Boosted mod: no $list-group-item-color-scale
// Boosted mod: no $list-group-hover-bg
$list-group-active-color: $white; // Boosted mod
$list-group-active-bg: $black; // Boosted mod
$list-group-active-border-color: $list-group-active-bg;
$list-group-disabled-color: $gray-500; // Boosted mod
$list-group-disabled-bg: $list-group-bg;
$list-group-action-color: $black; // Boosted mod
$list-group-action-hover-color: $accessible-orange; // Boosted mod
$list-group-action-active-color: $list-group-active-color; // Boosted mod
$list-group-action-active-bg: $list-group-active-bg; // Boosted mod
Variables for the dark list group:
$list-group-dark-color: $white; // Boosted mod
$list-group-dark-bg: $black; // Boosted mod
$list-group-dark-border-color: $gray-700; // Boosted mod
$list-group-dark-action-color: $white; // Boosted mod
$list-group-dark-action-hover-color: $primary; // Boosted mod
$list-group-dark-action-active-color: $black; // Boosted mod
$list-group-dark-action-active-bg: $white; // Boosted mod
$list-group-dark-disabled-color: $gray-700; // Boosted mod
$list-group-dark-disabled-bg: $list-group-dark-bg; // Boosted mod
$list-group-dark-active-color: $black; // Boosted mod
$list-group-dark-active-bg: $list-group-dark-action-active-bg; // Boosted mod
$list-group-dark-active-border-color: $list-group-dark-active-bg; // Boosted mod
Mixins
Used in combination with $theme-colors
to generate the contextual variant classes for .list-group-item
s.
@mixin list-group-item-variant($state, $background, $color) {
.list-group-item-#{$state} {
color: $color;
background-color: $background;
&.list-group-item-action {
&:hover,
&:focus {
color: $color;
background-color: if($color == $white, shade-color($background, 10%), tint-color($background, 10%)); // Boosted mod
}
// Boosted mod: no variant for active state
}
}
}
Loop
Loop that generates the modifier classes with the list-group-item-variant()
mixin.
// List group contextual variants
//
// Add modifier classes to change text and background color on individual items.
// Organizationally, this must come after the `:hover` states.
@each $color, $value in $background-colors {
@include list-group-item-variant($color, $value, color-contrast($value));
}
JavaScript behavior
Use the tab JavaScript plugin—include it individually or through the compiled boosted.js
file—to extend our list group to create tabbable panes of local content.
<div class="row">
<div class="col-4">
<div class="list-group" id="list-tab" role="tablist">
<a class="list-group-item list-group-item-action active" id="list-home-list" data-bs-toggle="list" href="#list-home" role="tab" aria-controls="list-home">Home</a>
<a class="list-group-item list-group-item-action" id="list-profile-list" data-bs-toggle="list" href="#list-profile" role="tab" aria-controls="list-profile">Profile</a>
<a class="list-group-item list-group-item-action" id="list-messages-list" data-bs-toggle="list" href="#list-messages" role="tab" aria-controls="list-messages">Messages</a>
<a class="list-group-item list-group-item-action" id="list-settings-list" data-bs-toggle="list" href="#list-settings" role="tab" aria-controls="list-settings">Settings</a>
</div>
</div>
<div class="col-8">
<div class="tab-content" id="nav-tabContent">
<div class="tab-pane fade show active" id="list-home" role="tabpanel" aria-labelledby="list-home-list">...</div>
<div class="tab-pane fade" id="list-profile" role="tabpanel" aria-labelledby="list-profile-list">...</div>
<div class="tab-pane fade" id="list-messages" role="tabpanel" aria-labelledby="list-messages-list">...</div>
<div class="tab-pane fade" id="list-settings" role="tabpanel" aria-labelledby="list-settings-list">...</div>
</div>
</div>
</div>
Using data attributes
You can activate a list group navigation without writing any JavaScript by simply specifying data-bs-toggle="list"
or on an element. Use these data attributes on .list-group-item
.
<div role="tabpanel">
<!-- List group -->
<div class="list-group" id="myList" role="tablist">
<a class="list-group-item list-group-item-action active" data-bs-toggle="list" href="#home" role="tab">Home</a>
<a class="list-group-item list-group-item-action" data-bs-toggle="list" href="#profile" role="tab">Profile</a>
<a class="list-group-item list-group-item-action" data-bs-toggle="list" href="#messages" role="tab">Messages</a>
<a class="list-group-item list-group-item-action" data-bs-toggle="list" href="#settings" role="tab">Settings</a>
</div>
<!-- Tab panes -->
<div class="tab-content">
<div class="tab-pane active" id="home" role="tabpanel">...</div>
<div class="tab-pane" id="profile" role="tabpanel">...</div>
<div class="tab-pane" id="messages" role="tabpanel">...</div>
<div class="tab-pane" id="settings" role="tabpanel">...</div>
</div>
</div>
Via JavaScript
Enable tabbable list item via JavaScript (each list item needs to be activated individually):
const triggerTabList = document.querySelectorAll('#myTab a')
triggerTabList.forEach(triggerEl => {
const tabTrigger = new boosted.Tab(triggerEl)
triggerEl.addEventListener('click', event => {
event.preventDefault()
tabTrigger.show()
})
})
You can activate individual list item in several ways:
const triggerEl = document.querySelector('#myTab a[href="#profile"]')
boosted.Tab.getInstance(triggerEl).show() // Select tab by name
const triggerFirstTabEl = document.querySelector('#myTab li:first-child a')
boosted.Tab.getInstance(triggerFirstTabEl).show() // Select first tab
Fade effect
To make tabs panel fade in, add .fade
to each .tab-pane
. The first tab pane must also have .show
to make the initial content visible.
<div class="tab-content">
<div class="tab-pane fade show active" id="home" role="tabpanel">...</div>
<div class="tab-pane fade" id="profile" role="tabpanel">...</div>
<div class="tab-pane fade" id="messages" role="tabpanel">...</div>
<div class="tab-pane fade" id="settings" role="tabpanel">...</div>
</div>
Methods
Asynchronous methods and transitions
All API methods are asynchronous and start a transition. They return to the caller as soon as the transition is started but before it ends. In addition, a method call on a transitioning component will be ignored.
Activates your content as a tab element.
You can create a tab instance with the constructor, for example:
const bsTab = new boosted.Tab('#myTab')
Method | Description |
---|---|
dispose |
Destroys an element’s tab. |
getInstance |
Static method which allows you to get the tab instance associated with a DOM element, you can use it like this: boosted.Tab.getInstance(element) . |
getOrCreateInstance |
Static method which returns a tab instance associated to a DOM element or create a new one in case it wasn’t initialized. You can use it like this: boosted.Tab.getOrCreateInstance(element) . |
show |
Selects the given tab and shows its associated pane. Any other tab that was previously selected becomes unselected and its associated pane is hidden. Returns to the caller before the tab pane has actually been shown (i.e. before the shown.bs.tab event occurs). |
Events
When showing a new tab, the events fire in the following order:
hide.bs.tab
(on the current active tab)show.bs.tab
(on the to-be-shown tab)hidden.bs.tab
(on the previous active tab, the same one as for thehide.bs.tab
event)shown.bs.tab
(on the newly-active just-shown tab, the same one as for theshow.bs.tab
event)
If no tab was already active, then hide.bs.tab
and hidden.bs.tab
events will not be fired.
Event type | Description |
---|---|
hidden.bs.tab |
This event fires after a new tab is shown (and thus the previous active tab is hidden). Use event.target and event.relatedTarget to target the previous active tab and the new active tab, respectively. |
hide.bs.tab |
This event fires when a new tab is to be shown (and thus the previous active tab is to be hidden). Use event.target and event.relatedTarget to target the current active tab and the new soon-to-be-active tab, respectively. |
show.bs.tab |
This event fires on tab show, but before the new tab has been shown. Use event.target and event.relatedTarget to target the active tab and the previous active tab (if available) respectively. |
shown.bs.tab |
This event fires on tab show after a tab has been shown. Use event.target and event.relatedTarget to target the active tab and the previous active tab (if available) respectively. |
const tabElms = document.querySelectorAll('a[data-bs-toggle="list"]')
tabElms.forEach(tabElm => {
tabElm.addEventListener('shown.bs.tab', event => {
event.target // newly activated tab
event.relatedTarget // previous active tab
})
})