JSFiddle - React, Tailwind, and code Playground

HTML

<li><a class="menuItem" href="#">PRODUCTGROEPEN</a> <div class="dropdown">asdfasdfasdfasdfasdfasdf</div></li>
<li><a class="menuItem" href="#">PRODUCTGROEPEN</a><div class="dropdown">asdfasdfasdfasdfasdfasdf</div></li>
<li><a class="menuItem" href="#">PRODUCTGROEPEN</a><div class="dropdown">asdfasdfasdfasdfasdfasdf</div></li>

CSS

.dropdown {
display: none;
}

.dropdown.active {
    display: block;
}

JavaScript

$('.menuItem').on('mouseover', function(){
    $(this).siblings('.dropdown').addClass('active');
});

$('.menuItem').on('mouseout', function(){
    $(this).siblings('.dropdown').removeClass('active');
});