Get distance between two points (return distance in meters)

haversine.js

const calculateDistance = (pointA, pointB) => {

  // http://www.movable-type.co.uk/scripts/latlong.html
  const lat1 = pointA.coordinate.latitude;
  const lon1 = pointA.coordinate.longitude;

  const lat2 = pointB.coordinate.latitude;
  const lon2 = pointB.coordinate.longitude;

  const R = 6371e3; // earth radius in meters
  const φ1 = lat1 * (Math.PI / 180);
  const φ2 = lat2 * (Math.PI / 180);
  const Δφ = (lat2 - lat1) * (Math.PI / 180);
  const Δλ = (lon2 - lon1) * (Math.PI / 180);

  const a = (Math.sin(Δφ / 2) * Math.sin(Δφ / 2)) +
            ((Math.cos(φ1) * Math.cos(φ2)) * (Math.sin(Δλ / 2) * Math.sin(Δλ / 2)));
  
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

  const distance = R * c;
  return distance; // in meters
}