qr.html

<!DOCTYPE html>
<html>
<head>
<link rel="shortcut icon" href="#" />
<style>
.center { 
  height:90vh;
  position: relative;
}

.center a {
  font-family: Tahoma, Verdana, Arial, sans-serif;
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  color: grey;
}

.gray {
  color: grey;
}
</style>

</head>
<body>
<p><a href="./" class="gray">Change Machine ID</a></p>
<div class="center"><a id="qrcode"></a></div>
</body>

<script src="qrcode.js"></script>
<script type="text/javascript">

function getCookie(name) {
    var nameEQ = name + "=";
    var ca = document.cookie.split(';');
    for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
    }
    return null;
}
function eraseCookie(name) {   
    document.cookie = name+'=; Max-Age=-99999999;';  
}

var x = getCookie('machineId');
if (x) {
    var urlBase = location.href.substring(0, location.href.lastIndexOf("/")+1)
    new QRCode(document.getElementById("qrcode"), urlBase + x);
}


</script>
</html>