How to switch Back camera from Font camera?

[anturj]

Hi, I am trying to develop a QR login system and i found a script https://github.com/moemoe89/simple-login-qrcode-webcam-php here and the problem is when i run this script from my mobile the font camera is turn on but i want to turn on the back camera.

I think the function is in main.js file. Will you please help me to how to turn on the Back camera ?

function setwebcam()
{
	document.getElementById("result").innerHTML="- scanning -";
    if(stype==1)
    {
        setTimeout(captureToCanvas, 500);    
        return;
    }
    var n=navigator;
    document.getElementById("outdiv").innerHTML = vidhtml;
    v=document.getElementById("v");

    if(n.getUserMedia)
        n.getUserMedia({video: true, audio: false}, success, error);
    else
    if(n.webkitGetUserMedia)
    {
        webkit=true;
        n.webkitGetUserMedia({video: true, audio: false}, success, error);
    }
    else
    if(n.mozGetUserMedia)
    {
        moz=true;
        n.mozGetUserMedia({video: true, audio: false}, success, error);
    }

    //document.getElementById("qrimg").src="qrimg2.png";
    //document.getElementById("webcamimg").src="webcam.png";
    document.getElementById("qrimg").style.opacity=0.2;
    document.getElementById("webcamimg").style.opacity=1.0;

    stype=1;
    setTimeout(captureToCanvas, 500);
}

I really need it. If you know any QR login script well then also let me know.
Thanks in advance friend.