Accessible carrousel using ARIA and Vanilla Javascript

Robust and accessible

As it relies on a basic HTML structure (Hx and contents), even if the JavaScript isn’t loaded, your page will work, it’s the miracle of progressive enhancement;
It is based on ARIA Design Pattern for tabs, a bit enhanced;
No inline CSS/JavaScript injected, your DOM stays clean, which is cool for responsive or CSP

It’s (highly) customisable

You can style it as you want;
You can set up transitions or animations… as you want;
You can create namespaces for generated classes if you need different behaviours in the same page;
Every aspect of the script can be customized, if you transpile the script into ES5, it will be IE9+ compatible.

Free and no license problem

No license problem: it uses MIT license, so it’s free, open-source and you can do whatever you want with it, including commercial use. This permission notice shall be included in all copies or substantial portions of it.
However, it is not prohibited to tell me that you’ve used it, or send me a little “thank you”. ;)

Lightweight

31kb (development, readable by humans);
~8kb (minified, readable by machines);
~3kb minified and gzipped (readable by… mutants‽‽)

Here is the starting code needed. Add the script, needed CSS, style it as you want, and it is ok.

<div class="js-carrousel relative">      
  <div class="js-carrousel__container mod--hidden" 
   data-carrousel-btn-previous-img="./left.svg"
   data-carrousel-btn-next-img="./right.svg"
   data-carrousel-btn-previous-text="Show previous content"
   data-carrousel-btn-next-text="Show next content"
   data-carrousel-prefix-class="news"
   data-carrousel-span-text-class="invisible"
   data-carrousel-transition="slide"
   data-carrousel-existing-hx="h3">
          
    <div class="js-carrousel__content">
      <h3>A first panel</h3>
      <p>Here the content.</p>
    </div><!--
 --><div class="js-carrousel__content">
      <h3>A second panel</h3>
      <p>Here the content.</p>
    </div><!--
 --><div class="js-carrousel__content">
      <h3>A third panel</h3>
      <p>Here the content.</p>
    </div>
          
  </div>
</div>

The plugin will do all the job on the fly:

Generate all needed ids, ARIA attributes and link everything that needs to;
Create buttons next and prev;
Generate the control list;
Add classes (namespaced if you have specified), in order to let you styling it as you want;
Add all listeners, etc.

The script is launched when the page is loaded. If you need to execute it on AJAX-inserted content, you may use for example on <div id="newContent">your carrousel source</div>:

van11yAccessibleCarrouselAria(document.getElementById('newContent')[, addListeners]);
addListeners is a facultative boolean (by default set to true) to add carrousel listeners (should be set up only the first time in most of the cases).

You may use npm command: npm i van11y-accessible-carrousel-aria.
You may also use bower: bower install van11y-accessible-carrousel-aria.

Then, follow the conventions given above. You may also copy/paste styles for carrousel design and styles for transitions.

Important note: for accessibility purposes (for VoiceOver), the plugin has to give focus to hx (h2, h3, h4, etc.) in tab contents. It is better having hx in each content tab.

If you have some, it is great, you just have to tell the plugin. In the example above, you tell it via data-carrousel-existing-hx.
And all these subtitles will be used in the ol list.
If you don’t have, nevermind, please tell the plugin which level of hx to use with data-carrousel-hx="hx", and it will insert an hx class="invisible" for you in each tab panel (you can “visually” hide them if needed with invisible class).
To specify the titles, use the attribute data-carrousel-span-text="Panel" and the plugin will create titles for each tab content: “Panel 1”, “Panel 2”, etc. And all these subtitles will be used in the ol list.

List of all data-attributes

data-carrousel-btn-previous-img: the address of the image used for “previous” button.
data-carrousel-btn-previous-text: the text of the “previous” button, will be put in the alt attribute if there is an image, and in the title attribute for the button.
data-carrousel-btn-next-img: the address of the image used for “next” button.
data-carrousel-btn-next-text: the text of the “next” button, will be put in the alt attribute if there is an image, and in the title attribute for the button.
data-carrousel-prefix-class: all the classes added for styling purpose will be prefixed, to simplify creating carrousel reusable styles.
data-carrousel-span-text-class: in the ol list, the text will be wrapped into a span with this class. Example, data-carrousel-span-text-class="yipikai":
```
<a … role="tab">
  <span class="yipikai">A robust base</span>
</a>
```
data-carrousel-transition: the value of this attribute will be added as a class on the carrousel container tag div class="js-carrousel__container". And CSS will do the magic to animate it. See three examples of transitions in the demo (“slide”, “fade” and “none”).
data-carrousel-active-slide: put here the number of the slide you want to display by default for your carrousel.
data-carousel-hide-arrows-focus: will make next/previous buttons not focusable for keyboard users and not visible for speech synthesis.

In this example page, I’ve used data-carrousel-prefix-class="news", so all the generated classes will start with .news-carrousel.

/* ------------------ example styles ------------------ */
.relative { position: relative; }
.mod--hidden { overflow: hidden; }

.invisible {
  border: 0;
  clip: rect(0 0 0 0);
  height: 1px;
  margin: -1px;
  overflow: hidden;
  padding: 0;
  position: absolute;
  width: 1px;
}

.news-carrousel__container {
  white-space: nowrap;
}
.news-carrousel__control__list {
  position: absolute;
  list-style-type: none;
  top: 100%;
  right: 0;
  left: 0;
  margin-top: -0.5em;
  padding-left: 0;
  text-align: center;
}
.news-carrousel__control__list__item {
  display: inline-block;
  margin: 0 .5em;
}
.news-carrousel__control__list__link {
  display: inline-block;
  width: 1em;
  height: 1em;
  background: #fff;
  border: 1px solid #148297;
  border-radius: 1em;
  cursor: pointer;
}

.news-carrousel__button-container {
  position: absolute;
}
.news-carrousel__button__previous {
  top: 50%;
  margin-top: -18px;
  left: 0;
  margin-left: -35px;
}
.news-carrousel__button__next {
  top: 50%;
  margin-top: -18px;
  right: 0;
  margin-right: -35px;
}
.news-carrousel__button__button {
  margin: 0;
  padding: 0;
  background: transparent;
  border: 0;
  cursor: pointer;
}

/* only for minimalist example */
.carrousel__content[aria-hidden=true] {
  display: none;
}
/* ------------------ State rules ------------------ */
.news-carrousel__control__list__link:focus,
.news-carrousel__control__list__link:hover,
.news-carrousel__control__list__link:active,
.news-carrousel__control__list__link[aria-selected=true] {
  background: #148297;
}
.news-carrousel__control__list__link:focus,
.news-carrousel__control__list__link:hover,
.news-carrousel__control__list__link:active {
  outline: 2px dotted #4d287f;
}

Here are 3 examples of transitions:

/* ------------------ transition slide ------------------ */
.slide .carrousel__content {
  display: inline-block;
  vertical-align: top;
  visibility: visible;
  width: 100%;
  position: relative;
  transition: visibility 0s ease, transform .5s ease-in;
  transition-delay: 0;
  white-space: normal;
}

[data-carrousel-active-slide="1"].slide > .carrousel__content {
  transform: translateX(0);
}
[data-carrousel-active-slide="2"].slide > .carrousel__content {
  transform: translateX(-100%);
}
[data-carrousel-active-slide="3"].slide > .carrousel__content {
  transform: translateX(-200%);
}
[data-carrousel-active-slide="4"].slide > .carrousel__content {
  transform: translateX(-300%);
}
[data-carrousel-active-slide="5"].slide > .carrousel__content {
  transform: translateX(-400%);
}
[data-carrousel-active-slide="6"].slide > .carrousel__content {
  transform: translateX(-500%);
}
[data-carrousel-active-slide="7"].slide > .carrousel__content {
  transform: translateX(-600%);
}
[data-carrousel-active-slide="8"].slide > .carrousel__content {
  transform: translateX(-700%);
}
[data-carrousel-active-slide="9"].slide > .carrousel__content {
  transform: translateX(-800%);
}

[data-carrousel-active-slide].slide > [aria-hidden="true"].carrousel__content {
  visibility: hidden;
  transition-delay: .5s, 0s;
}


/* ------------------ transition fade ------------------ */
.fade .carrousel__content {
  -webkit-animation: fadein 1s;
  animation:         fadein 1s;
  white-space: normal;
}
.fade .carrousel__content[aria-hidden=true] {
  -webkit-animation: fadeout 1s;
  animation:         fadeout 1s;
}
.fade .carrousel__content[aria-hidden=true] {
  display: none;
}

@keyframes fadeout {
  0%   { opacity: 1; }
  100% { opacity: 0; }
}
@keyframes fadein {
  0%   { opacity: 0; }
  100% { opacity: 1; }
}



/* ------------------ transition none ------------------ */
.none .carrousel__content {
  white-space: normal;
}
.none .carrousel__content[aria-hidden=true] {
  display: none;
}

Keyboard navigation is supported too, here are the shortcuts:

If you focus on the carrousel “buttons” (not “next” and “previous” buttons, on the control list):

use Up/Left to see previous carrousel tab;
use Down/Right to see next carrousel tab;
use Home to see first carrousel tab (wherever you are in carrousel tab buttons);
use End to see last carrousel tab (wherever you are in carrousel tab buttons).

If you focus in a carrousel content:

use Ctrl Up to set focus on the carrousel button for the currently displayed carrousel content.

Panel opened by default

You may specify on js-carrousel__container the attribute data-carrousel-active-slide="The number of the panel". Example: data-carrousel-active-slide="2" will display the second panel by default. In the carrousel demo, the third example shows it.

Accessible carrousel using ARIA

Robust and accessible

It’s (highly) customisable

Free and no license problem

Lightweight

How it is working

How to use it

List of all data-attributes

How to style it (nicely)

How to style transitions (nicely)

Keyboard shortcuts

Bonuses

Panel opened by default