JSFiddle - React, Tailwind, and code Playground

HTML

<div id="linkcontainer">
    <a href="http://news.ycombinator.com/">yc</a>
    <a href="http://asdf.com">asdf</a>
</div>
<canvas id="canvas" width="50" height="50"></canvas>

CSS

a {
    color:red;
    display:block;
}
a:visited {
    color:green;
}

#linkcontainer,
#canvas {
    position:absolute;
    left:0;
    top:0;
}

JavaScript

var canvas = document.getElementById('canvas').getContext('2d');

canvas.fillStyle = "rgb(0, 0, 255)";
canvas.globalAlpha = 0.2;

canvas.fillRect(0, 0, 50, 50);
var imgdata = canvas.getImageData(0, 0, 50, 50);

function LinkFilter(d) {
    console.log(d);
    return ( d != 0 && d != 50 && d != 255 );
}

function VisitedFilter(d) {
    console.log(d);
    return ( d != 0 && d != 50 && d != 255 && d != 51 );
}


console.log('links',Array.prototype.filter.call(imgdata.data, LinkFilter));
console.log('visited',Array.prototype.filter.call(imgdata.data, VisitedFilter));