JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/dot-luv/jquery-ui.css">
<ul>
  <li>Item</li>
  <li> Item with Sub
     <ul>
        <li>Item</li>
        <li> Item with Sub
           <ul>
              <li>Item</li>
            </ul>
        </il>
            </ul>
            </li>
         </ul>

CSS

li { padding-left: 10px; }
li ul { display: none; }

JavaScript

$("li").hover(function() {
      $(this).children("ul").slideDown();
    }, function() {
      $(this).children().slideUp();
    });