How can I get referral params QR code messenger

well I use Generator a parametric code QR for my chatbot (messenger). That is my code for that:

function setQRcode() {
 requestData = {
  "type": "standard",
  "data": {
    "ref":"XXXXXXXXXXX"
          },
  "image_size": 1000
    }
    request({
     url: "https://graph.facebook.com/v2.6/me/messenger_codes?access_token=" + pageAccessToken,
        method: "POST",
        json: requestData
    }, function (error, response, body) {
        
            console.log(body.uri)  
    });
}

My problem is that I couldn't find how can I get and use the values of my file referral.ref in my app.js ?

via Oualid Barjani