JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="liste">
  <li>1 Lorem</li>
  <li>2 ipsum</li>
  <li>3 dolor</li>
  <li style="display:none;">4 sin amet</li>
  <li>5 consectetur</li> <!-- add a lastli class here -->
  <li>6 aliquam</li>
  <li style="display:none;">7 lobortis</li>
  <li>8 Fusce</li>
  <li>9 fringilla</li>
  <li>10 rutrum</li> <!-- add a lastli class here -->
  <li>11 dapibus</li>
  <li style="display:none;">12 nunc</li>
  <li>13 nunc</li>
</ul>

CSS

.lastli {
	color : red;
}

JavaScript

$(document).ready(function() {
	count=0;
	$('li:visible').each(function(i, e) {
		count=count+1;		
		if (count==4) {
			$(e).addClass('lastli');
			count=0;
		}
	});
});