function setRentacle() {
  const bounds = map.getBounds();

  // update info about bounds
  updateInfo(bounds._northEast, bounds._southWest);

  // set rentacle
  L.rectangle(bounds, {
    color: randomColor(),
    weight: 20,
    fillOpacity: 0.1,
  }).addTo(map);

  // set map
  map.fitBounds(bounds);
}
Obtaining coordinates of the visible map