main.js not sending JSON to server.py

@app.route('/predict', methods=["GET"])

def predict():

    json = request.get_json()

    print(json)

    message = json["message"]

    return message # just for debugging, for now... TODO integrate the code with ml.py to get a response

// todo fix this to actually send the message data

function getPrediction() {

    var url = "http://localhost:8080"

    var endpoint = "/predict"

    var data = JSON.stringify({

        "message": "Hi"

      });

      var xhr = new XMLHttpRequest();

      xhr.withCredentials = true;

      xhr.addEventListener("readystatechange", function () {

        if (this.readyState === 4) {

          console.log(this.responseText);

        }

      });

      xhr.open("GET", "http://localhost:8080/predict");

      xhr.setRequestHeader("Content-Type", "application/json");

      xhr.setRequestHeader("User-Agent", "PostmanRuntime/7.19.0");

      xhr.setRequestHeader("Accept", "*/*");

      xhr.setRequestHeader("Cache-Control", "no-cache");

      xhr.setRequestHeader("Postman-Token", "25701512-a7b7-46d3-b614-d82adfe63972,89b19c6f-e712-4c75-9485-f81c5d2b9d3c");

      xhr.setRequestHeader("Host", "localhost:8080");

      xhr.setRequestHeader("Accept-Encoding", "gzip, deflate");

      xhr.setRequestHeader("Content-Length", "20");

      xhr.setRequestHeader("Connection", "keep-alive");

      xhr.setRequestHeader("cache-control", "no-cache");

      xhr.send(data);

    /*

    var url = "http://localhost:8080";

    var endpoint = "/predict";

    var http = new XMLHttpRequest();

    var data = JSON.stringify({

        "message": document.getElementById("message").value

    });

    http.open("GET", url + endpoint, true);

            // JSON -> JS obj

            replyObj = JSON.parse(replyString);

            // change the prediction label

            document.getElementById("prediction").innerText = replyObj.prediction;  // signifies that we need a string called prediction from the backend

        }

        else {

            console.log("Error getting prediction from the backend server. (Is it running?)");

        }

    }

    http.send(data);

    */

}

// todo fix this to actually send the message data