JSFiddle - React, Tailwind, and code Playground

by crucify

HTML

<p class="p em">
em em em
</p>
<p class="p rem">
rem rem rem
</p>
<p class="p percent">
% % %
</p>
<p id="result">

</p>

CSS

.em { font-size: 1.123456789em; }
.rem { font-size: 1.123456789rem; }
.percent { font-size: 1.123456789%; }

JavaScript

var ps = document.querySelectorAll('.p'), result = [];
for(var i = 0; i < ps.length; i ++) {
  result.push(document.defaultView.getComputedStyle(ps[i], '').fontSize);
}
document.getElementById('result').innerText = result.join('<br>');