JSFiddle - React, Tailwind, and code Playground

HTML

<div id="tabs">
   <ul class="clearfix">
      <li><a href="#"><span>Tab 1</span></a></li>
      <li><a href="#"><span>Tab 2</span></a></li>
      <li><a href="#"><span>Tab 3</span></a></li>
   </ul>

   <div>Content 1</div>
   <div>Content 2</div>
   <div>Content 3</div>
</div>

JavaScript

$(document).ready(function(){
    $('li a').click(function(e){
        var $li = $(this).parents('li');
        var $ul = $(this).parents('ul');
        alert($ul.children().index($li));
    });
});