JSFiddle - React, Tailwind, and code Playground

HTML

<div id="box" class="">Lorem ipsum</div>

<button>Action!</button>

CSS

div{
    position:absolute;
    top:30px;
    left:10px;
    width:200px;
    background:#f00;
    color:#000;
}


div.big{
    width:400px;
    background:#0f0;
}

JavaScript

$(function(){
    $("button").click(function(){
        $("#box").toggleClass("big","slow");
    });
});