JSFiddle - React, Tailwind, and code Playground

HTML

<p>This is the link's colour that we will be trying to get:</p>
<a id="link" href="http://jsfiddle.net/WK_of_Angmar/NW7kR/">LINK</a>
<p>This box will be set to the colour that the web browser has stated the link is. If the colour is the same, then it is likely that history has been leaked via CSS/JS (unless you or the browser vendor have set the default link colour to orange (seriously?)).</p>
<div id="box"></div>
<p><strong>TL;DR? If the colour of the link and the box are different, it's probably fine.</strong></p>

CSS

a:visited {
    color: orange !important;
}

#box {
    width: 100px;
    height: 100px;
}

strong {
    font-weight: bold;
}

p, a, div {
    margin: 10px;
}

JavaScript

var elem = document.getElementById("link");
document.getElementById("box").style.backgroundColor = window.getComputedStyle(elem,null).getPropertyValue("color");