JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://webqr.com/llqrcode.js"></script>
<video autoplay></video>
<canvas id="qr-canvas"></canvas>

CSS

video{
    display:none;
}

JavaScript

if (navigator.webkitGetUserMedia) {
    navigator.webkitGetUserMedia("video", function(stream) {
        var video = document.querySelector("video");
        video.src = webkitURL.createObjectURL(stream);
        var callback = function() {
            var canvas = document.querySelector("canvas"),
                ctx = canvas.getContext("2d");
            console.dir(video);
            var height = video.videoHeight,
                width = video.videoWidth;
            canvas.width = width;
            canvas.height = height;
            qrcode.callback = function(msg) {
                alert(msg);
            };
            setInterval(function() {
                ctx.drawImage(video, 0, 0, width, height);
                try {
                    qrcode.decode();
                } catch (x) {

                }
            }, 150);
        };
        video.addEventListener("play", callback, false);

    });
}
else {
    alert("No camera support :(\nTry Google Chrome Canary!");
}