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>Grandparent
        <ul>
          <li> Child1 
              <ul><li> Grandchild11</li></ul>
          </li>
          <li> Child2 
              <ul><li>GrandChild21</li><li>grandchild22</li></ul>
          </li>
        </ul>
    </li>
</ul>

CSS

ul li ul { display: none; }

JavaScript

$('li').click(function(e){
  $(this).children('ul').slideToggle();
  e.stopPropagation();
});