JSFiddle - React, Tailwind, and code Playground

HTML

<h4>Counting up height of Elements inside red bordered div</h4>

<div class="preview">
  <span class="intro-breaker">Lorem ipsum, <br/></span>
  <span class="intro-breaker"><br/></span>
  <span class="intro-breaker">Lorem ipsum doilor sit amet <br/></span>
  <span class="intro-breaker">Lorem ipsum sit amet dolores eunt sunt. Lorem ipsum sit amet dolores eunt sunt. Lorem ipsum sit amet dolores eunt sunt. Lorem ipsum sit amet dolores eunt sunt. <br/></span>
  <span class="intro-breaker"><br/></span>
  <span class="intro-breaker">Lorem ipsum doilor sit amet <br/></span>
</div>

<input type="text" id="t" value="0">

CSS

.preview { line-height: 14px; font-size: 12px; border: 1px solid #c00; }

JavaScript

$( document ).ready(function() {
var ct = 0;
$('.preview').children().each(function() {
	ct = ct+$(this).outerHeight(true);
});

$('#t').val(ct+"px - total height");
});