const updateCoordinates = e => { 
  if(coordinates.x === undefined || coordinates.y === undefined){
    coordinates.x = e.x; 
    coordinates.y = e.y;
    addElement(); 
  }

  if(Math.abs(coordinates.x - e.x) > 50 || Math.abs(coordinates.y - e.y) > 50) {
    coordinates.x = e.x; 
    coordinates.y = e.y;
    addElement(); 
  } 
}

header.addEventListener('mousemove', e => {
  updateCoordinates(e); 
});