JSFiddle - React, Tailwind, and code Playground

HTML

<div id="navigation">
    <ul>
        <li class="menu-item-parent"><a href="#">Top level 1</a>
            <ul>
                <li><a href="#">Submenu 1</a></li>
                <li><a href="#">Submenu 2</a></li>
            </ul>
        </li>
        <li class="menu-item-parent"><a href="#">Top level 2</a>
            <ul>
                <li><a href="#">Submenu 1</a></li>
                <li><a href="#">Submenu 2</a></li>
            </ul>
        </li>
    </ul> 
</div>

CSS

#navigation ul li {
    display: inline-block;
}    
#navigation ul ul {
    display: none;
    position: absolute;
}

JavaScript

$(function() {
     $("#navigation .menu-item-parent").click(function(){
         $(this).children('ul').toggle();
     })
 });