JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
 <li>Menu 1<ul><li>submenu1</li><li>Submenu2</li></ul></li>
 <li>Menu 2<ul><li>submenu1</li><li>Submenu2</li></ul></li> 
 <li>Menu 3<ul><li>submenu1</li><li>Submenu2</li></ul></li>
 </ul>

CSS

li 
{
    background:black;
    padding:5px;
    width:100px;
    color:white;
    border:1px solid white;
    cursor:pointer;

}
li ul
{
    display:none;
}
li ul li
{
    width:100px;
    border:0px;
    padding:0px;
}

JavaScript

$('ul li').click(function() {
    if($(this).children().css("display")=='none'){
          $('li').children().slideUp();
          $(this).children().slideToggle();
}
});