JSFiddle - React, Tailwind, and code Playground

HTML

<div>1</div>
<div>2</div>
<div>3</div>
<div>4</div>
<div class="foo">5</div>

CSS

.red {
    color: #C00;
}

JavaScript

var $el = $('.foo');

var $next = $el.next()
if ($next.length == 0)
    $next = $el.siblings().first();

$next.addClass('red');