JS: Haversine Formula Distance Between Lat,Lng Points in Km

JS: Haversine Formula Distance Between Lat,Lng Points in Km

function getDistanceFromLatLonInKm(lat1,lon1,lat2,lon2) {
	var R = 6371; // Radius of the earth in km
	var dLat = deg2rad(lat2-lat1);  // deg2rad below
	var dLon = deg2rad(lon2-lon1);
	var a = Math.sin(dLat/2) * Math.sin(dLat/2) + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * 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;
}