JSFiddle - React, Tailwind, and code Playground

HTML

<div class='box'></div>

CSS

.box {
    width: 250px;
    height: 100px;
    border: 1px #000 solid;
}

.red {
    background: red;
}

.blue {
    background: blue;
}

JavaScript

$('div').click(function() {
    $(this).addClass('red');
});