JSFiddle - React, Tailwind, and code Playground

HTML

<div id='foo'>
    <div id="bar"></div>
</div>

CSS

#foo {
    width: 100px;
    height: 50px;
    background: red;   
}

#bar {
    width: 10px;
    height: 10px;
    background: blue;
    display:none;
}

JavaScript

$("#foo").live("hover", function(e) {
    $("#bar").toggle();
});