Simple Responsive Menu using Foundation Visibility Classes and Vanilla Javascript

responsive-menu.html

<!-- Button -->
<button id="menu-button" class="hide-for-medium">Menu</button>

<!-- Menu -->
<div id="menu" class="show-for-medium">
  <ul>
    <li><a href="#">Link One</a></li>
    <li><a href="#">Link Two</a></li>
    <li><a href="#">Link Three</a></li>
  </ul>
</div>

<script>
var button = document.querySelector('#menu-button');
var menu = document.querySelector('#menu');

button.addEventListener('click', function (event) {
    menu.classList.toggle("show-for-medium");
  }
);
</script>