Calculate distance in km between 2 positions

calculate-distance-in-km.ts

export function getDistanceFromLocationsInKm(
  latStart: number,
  longStart: number,
  latEnd: number,
  longEnd: number
): number {
  const R = 6371; // Radius of the earth in km
  const dLat = _deg2rad(latEnd - latStart);
  const dLong = _deg2rad(longEnd - longStart);
  const a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(_deg2rad(latStart)) * Math.cos(_deg2rad(latEnd)) * Math.sin(dLong / 2) * Math.sin(dLong / 2);
  const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  const d = R * c; // Distance in km

  return +d.toFixed(2);
}

function _deg2rad(deg) {
  return deg * (Math.PI / 180);
}