JSFiddle - React, Tailwind, and code Playground

HTML

<button id="btn-foo">Add</button>
<hr>
<div id="renderer">
  <div id="fields_1" class="items"><span>Lorem ipsum dolor sit amet.</span></div>
</div>

JavaScript

$('#btn-foo').on('click', function() {
	var lastItem = $('#renderer .items:last'),
  	lastID = parseInt(lastItem.attr('id').replace('fields_', ''));
  $('#renderer').append(lastItem.clone().attr('id', "fields_" + (lastID + 1)));
});