JSFiddle - React, Tailwind, and code Playground

HTML

<div id="top-nav">
 <ul>
  <li><span>Products &amp; Services</span>
    <ul>
      <li><div class="megamenu">Content here...</div></li>
    </ul>
  </li>
  <li><span>Support &amp; Training</span>
    <ul>
     <li> <div class="megamenu">Content here...</div></li>
    </ul>
  </li>
  <li><span>Communities</span>
    <ul>
     <li> <div class="megamenu">Content here...</div></li>
    </ul>
  </li>
  <li><span>Store</span>
    <ul>
      <li><div class="megamenu">Content here...</div></li>
    </ul>
  </li>
 </ul>
</div>

CSS

.megamenu {display:none}
span {cursor:pointer}
#closeButton {color:red;margin-left:10px}

JavaScript

$(function(){
    $('#top-nav span').click(function(){
        divTrigger = $('#top-nav span').index(this);
        thisMegaMenu = $('.megamenu:eq('+divTrigger+')');
        $('.megamenu').slideUp(200);
        if(thisMegaMenu.is(":not(':visible')")){
        thisMegaMenu.slideDown(200);
        }
});
});