JSFiddle - React, Tailwind, and code Playground

by Karim AG

HTML

<div id="ii"></div>

CSS

#ii:before {
    content:'b';
    display:block;
    height:100px;
    width:100px;
    background:#000;
}

JavaScript

$(document).ready(function () {
    var content = window.getComputedStyle(document.querySelector('#ii'), ':before').getPropertyValue('content');
    alert(content);
});