JSFiddle - React, Tailwind, and code Playground

HTML

<span id="hoverMe">Hover</span>
<div style="width:100px; height:100px; background-color:#000; display:none" id="expand"></div>

JavaScript

$("#hoverMe").hover(function() {
    $("#expand").stop(true, true).slideDown();
}, function() {
    $("#expand").stop(true, true).slideUp();
});