JSFiddle - React, Tailwind, and code Playground

HTML

<div id="box"></div>

CSS

#box {
    width: 90px;
    height: 14px;
    background-color: #444;
}

#box.activated {
    background-color: #ccc;
}

JavaScript

$('#box').on('click', function() {
    $(this).toggleClass('activated');
});