Distance of two points on a sphere

// Distance of two points on the terrestrial sphere (distance in km, azimut in °)

var result = distance({
    lon1: 7.34684,
    lat1: 47.36376,
    lon2: 7.60884,
    lat2: 47.52812
});
console.log(result);

function distance({ lon1, lon2, lat1, lat2}) {

  let azimut, dist;
  const RADIANS = 0.017453292519943295769236907684886;  // = π / 180°
  const NAUTICAL_MILE = 1.852216;                       // = 1′ of arc in km

  lon1 = lon1 * RADIANS;
  lon2 = lon2 * RADIANS;
  lat1 = lat1 * RADIANS;
  lat2 = lat2 * RADIANS;

  // Compute the distance arc of distance using the cosine law for spherical triangles
  let a = Math.acos(
            Math.sin( lat1 ) * Math.sin( lat2 ) +
            Math.cos( lat1 ) * Math.cos( lat2 ) * Math.cos( lon1 - lon2 ) );

  // Shortest distance in km
  dist = a * 60 * NAUTICAL_MILE / RADIANS;

  // Azimut
  azimut = a < 1e-4 ? 0 :
     Math.atan2(
       Math.cos( lat1 ) * Math.sin( lon2-lon1 ),
       Math.sin( lat2 ) * Math.cos( lat1 ) - Math.cos( lon2-lon1 ) * Math.cos( lat2 ) * Math.sin( lat1 )
     ) / RADIANS;

  if (azimut < 0) azimut += 360;

  return {azimut,dist};

}