JSFiddle - React, Tailwind, and code Playground

HTML

<button>test</button>
<div class="collapse">test</div>

CSS

.collapse {
    opacity:0;
    transition: opacity 1s linear;
}
.collapse.in {
    opacity:1;
}

JavaScript

$(document).ready(function(){
    $("button").click(function(){
        $(".collapse").toggleClass(".collapse in", 5000);
    });
});