Distance between two coordinates

coordinates_distance.js

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

   const R = 6371e3; // metres
   const Q1 = lat1 * Math.PI / 180;
   const Q2 = lat2 * Math.PI / 180;
   const DP = (lat2 - lat1) * Math.PI / 180;
   const DA = (lon2 - lon1) * Math.PI / 180;

   const a = Math.sin(DP / 2) * Math.sin(DP / 2) +
      Math.cos(Q1) * Math.cos(Q2) *
      Math.sin(DA / 2) * Math.sin(DA / 2);

   const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

   const d = R * c; // in metres

   return d
}

function walkingEta(d) {
	var hrsdec = d / 1000 / 5.1
  var hrs = Math.floor(hrsdec);
  var minsdec = (hrsdec - hrs) * 60;
  return Math.round(minsdec);
}

const d = distance(21.230097, 45.758419, 21.229034, 45.757978);
const mins = walkingEta(d);

console.log(d + " meters distance")
console.log(mins + " minutes walking time")