JSFiddle - React, Tailwind, and code Playground

HTML

<div style="font-size:1.5em;">blaah</div>

JavaScript

$(function() {
    var computedStyles = window.getComputedStyle($('div')[0], null);
    var fontSize = computedStyles.getPropertyValue('font-size')
    $('body').append(fontSize);
    alert(window.getComputedStyle(o, null)[n]);
});