measure-geolocation/lib/DistanceCalculator.js

Utilty pacakage to find distance between different geographical locations

'use strict';
class DistanceCalculator{

/**
 * getDistanceBetweenLocations measure distance between two geoLocations in KM 
 * @param {Object{lat, lon}} source  
 * @param {Object{lat, lon}} destination 
 */  
getDistanceBetweenLocations(source, destination) {
      let R = 6371; // Radius of the earth in km
      let sLat = source.lat, sLon = source.lon; 
      let destLat = destination.lat, destLon = destination.lon;       
      let dLat = this.deg2rad(destLat - sLat);  // deg2rad below
      let dLon = this.deg2rad(destLon - sLon); 
      let a = 
        Math.sin(dLat/2) * Math.sin(dLat/2) +
        Math.cos(this.deg2rad(sLat)) * Math.cos(this.deg2rad(destLat)) * 
        Math.sin(dLon/2) * Math.sin(dLon/2) ; 

      var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
      var d = R * c; // Distance in km      
      return d;
    }
  
  //  degree to radian converter
  deg2rad(deg) {
      return deg * (Math.PI/180)
    }

}

module.exports = new DistanceCalculator();