Calc the distance in meters between two geo-points

geo-distance.js

function distance(p1, p2) {
  // radius of the sphere (Earth) in meters
  const rad = 6372795;

  // coordinates of two points
  const {lat: llat1, long: llong1} = p1;
  const {lat: llat2, long: llong2} = p2;

  // in radians
  const lat1 = llat1 * Math.PI / 180;
  const lat2 = llat2 * Math.PI / 180;
  const long1 = llong1 * Math.PI / 180;
  const long2 = llong2 * Math.PI / 180;

  // cosines and sines of latitudes and longitude differences
  const cl1 = Math.cos(lat1);
  const cl2 = Math.cos(lat2);
  const sl1 = Math.sin(lat1);
  const sl2 = Math.sin(lat2);
  const delta = long2 - long1;
  const cdelta = Math.cos(delta);
  const sdelta = Math.sin(delta);

  // calculating the length of a large circle
  const y = Math.sqrt(Math.pow(cl2 * sdelta, 2) + Math.pow(cl1 * sl2 - sl1 * cl2 * cdelta, 2));
  const x = sl1 * sl2 + cl1 * cl2 * cdelta;
  const ad = Math.atan2(y, x);
  const dist = ad * rad;
  return dist; // in meters
}