JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li><a href="#1">Элемент 1</a></li>
    <li><a href="#2">Элемент 2</a></li>
    <li><a href="#3">Элемент 3</a></li>
    <li><a href="#4">Элемент 4</a></li>
</ul>

JavaScript

$('ul').on('mouseenter mouseleave', function(evt){
    this.style.border = evt.type == 'mouseenter' ? '1px solid red' : '';
});