JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="navi">
    <li><a class="menu" href="#">About MHG</a></li>
    <li><a class="menu" href="#">Workout Programs</a></li>
    <li><a class="menu" href="#">Fitness Tips</a></li>
    <li><a class="menu" href="#">Contact Us</a></li>          
    <li><a class="menu" href="#">Read Our Blog</a></li>
  </ul>

CSS

.active
{
    background-color:green;
}

JavaScript

$('a.menu').click(function(){
    $('a.menu').removeClass("active");
    $(this).addClass("active");
});