JSFiddle - React, Tailwind, and code Playground
HTML
<div class="box">
<div class="change">
<h1>Box 1</h1>
<p>Lorem ipsum</p>
</div>
</div>
<div class="box">
<div class="change">
<h1>Box 2</h1>
<p>Lorem ipsum</p>
</div>
</div>
<div class="box">
<div class="change">
<h1>Box 3</h1>
<p>Lorem ipsum</p>
</div>
</div>
<div class="box">
<div class="change">
<h1>Box 4</h1>
<p>Lorem ipsum</p>
</div>
</div>
CSS
.box {width:45%; background:Red;float:left;margin:10px;}
JavaScript
var testimonialsArray = [
"<div class='change'><h1>Box 5</h1><p>Lorem ipsum</p></div>",
"<div class='change'><h1>Box 6</h1><p>Lorem ipsum</p></div>",
"<div class='change'><h1>Box 7</h1><p>Lorem ipsum</p></div>",
"<div class='change'><h1>Box 8</h1><p>Lorem ipsum</p></div>",
"<div class='change'><h1>Box 9</h1><p>Lorem ipsum</p></div>"
];
var order = Math.floor((Math.random()* $('.change').length )+1);
$('.box').eq(order).find('.change').fadeOut();
//testimonials[3]