JSFiddle - React, Tailwind, and code Playground

HTML

<div id="testimonial-container"><div class="testimonial">Here comes a testimonial</div>
    <div class="testimonial">Here comes another testimonial</div>
    <div class="testimonial">And another one</div>
    <ul class="testimonial-logos">
       <li><a><img src="logo-1.jpg" /></a></li>
       <li><a><img src="logo-2.jpg" /></a></li>
       <li><a><img src="logo-3.jpg" /></a></li>
    </ul>
</div>

CSS

.testimonial-logos { width : 60px; }
.active { background-color : blue; }

JavaScript

var $container = $("#testimonial-container"),
    $testimonials = $(".testimonial", $container).hide(),
    $prev;

$(".testimonial-logos li", $container).mouseenter(function() {
    if ($prev)
       $testimonials.eq( $prev.removeClass("active").index() ).hide();
    $testimonials.eq( ($prev = $(this).addClass("active")).index() ).show();
}).eq(0).mouseenter();