JSFiddle - React, Tailwind, and code Playground

HTML

<nav>
  <a href="#" class="toggle">Toggle Menu</a>
  <ul>
    <li>Menu Item</li>
    <li>Menu Item</li>
  </ul>
</nav>

CSS

nav {
  width: 100%;
  ul {
    display: none;
    width: 100%;
    &.expanded {
      display: block;
    }
  }
  .toggle {
    display: block !important;
  }
}

JavaScript

$(document).ready(function(){
  $("a.toggle").click(function(){
    $("nav ul").slideToggle(1500);
    $(this).toggleClass("open");
  });
});