JSFiddle - React, Tailwind, and code Playground

HTML

<div id="block"></div>

CSS

#block {
    width: 50px;
    height: 50px;
    background: red;
    visibility: hidden;
}

JavaScript

var block = $('#block');

function changecol() {
    block.animate({width: 100, height: 100}, 300, function() {
        block.animate({width: 50, height: 50}, 300, changecol);
    });
}

$(document).ready(function() {
    block.css('visibility', 'visible');
    changecol();
});