How to get the position data from the joystick to the flask server?

I would like to get the position data from the js joystick o use it at the flask server. I tried using ajax:

python:

@app.route(‘/test’, methods=[‘GET’, ‘POST’])
def test_ajax():

    if request.method == "POST":
        data = request.json
        print('data:', data)
        result = {'url': url_for('index')}
        print('result:', result)
        return jsonify(result)
    else:
        return render_template('index.html')

<div class="container fluid">
    
            <h1>Joystick</h1>
            
            <div id="joy1Div" style="width:200px;height:200px;margin-bottom:20px;"></div>
    
        </div>
        
        <script type="text/javascript">
                   
          var Joy1 = new JoyStick('joy1Div', {}, function(stickData) {
          joy1IinputPosX.value = stickData.xPosition;
          joy1InputPosY.value = stickData.yPosition;
          joy1Direzione.value = stickData.cardinalDirection;
          joy1X.value = stickData.x;
          joy1Y.value = stickData.y;
          });
            
        </script>
    
        <script>
    
          data = {'ID': 'foobar'};
          var joystick = document.getElementById('joy1Div');
          joy1X.onchange = function() {
            $.ajax({
              type: "POST",
              url: "/test",
              contentType: 'application/json;charset=UTF-8',
              data: JSON.stringify(data, null, 't'),
              dataType: 'json',
              success: function(data) {
                  window.location.href = data['url']
              },
              error: function(response) {
                  alert(response)
              },
          });
          }; 
    
        </script>

Every time the position of the joystick changed I would like to send the position data to flask