JSFiddle - React, Tailwind, and code Playground

HTML

<div class="a"></div><div class="b"></div><br/>
<div class="c"></div><div class="b"></div><br/>
<button>Fade in</button>

CSS

div {
    display: inline-block;
    width: 100px;
    height: 100px;
    background: #eee;
}
.a {
    display: none;
}

.b{
    background: #ccc;
}

.c {
    opacity: 0;
}

JavaScript

function go(){
    $('.a').fadeIn();
    $('.c').animate({opacity: 1});
}

$('button').click(go);