JSFiddle - React, Tailwind, and code Playground

HTML

<div id='foo'>
   <div class='btn 1'>
       <div class='a'></div><div class='b'></div>
   </div>
   <div class='btn 2'>
       <div class='a'></div><div class='b'></div>
   </div>
   <div class='btn 3'>
       <div class='a'></div><div class='b'></div>
   </div>
</div>

CSS

.btn {
    position: relative;
}
.btn .a {
    position: absolute;
    height: 20px;
    width: 50px;
    background: lightblue;
    display: none;
}
.btn {
    padding: 10px;;
}
.btn .b {
    height: 20px;
    width: 50px;
    background: coral;
    cursor: pointer;
}

JavaScript

var $btn = $('#foo > .btn');
$('#foo').on('click', '.btn', function() {
    $btn.find('.a').fadeOut();
    $(this).find('.a').fadeIn();
})