index.js
function dst(lat1, lon1, lat2, lon2) {
  // generally used geo measurement function
  var dLat = lat2 * Math.PI / 180 - lat1 * Math.PI / 180;
  var dLon = lon2 * Math.PI / 180 - lon1 * Math.PI / 180;
  var a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(lat1 * Math.PI / 180) *
      Math.cos(lat2 * Math.PI / 180) *
      Math.sin(dLon / 2) *
      Math.sin(dLon / 2);
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  var d = R * c;
  return d * 1000; // meters
}
function dst(lat1, lon1, lat2, lon2) {
  // generally used geo measurement function
  var dLat = lat2 * Math.PI / 180 - lat1 * Math.PI / 180;
  var dLon = lon2 * Math.PI / 180 - lon1 * Math.PI / 180;
  var a =
    Math.sin(dLat / 2) * Math.sin(dLat / 2) +
    Math.cos(lat1 * Math.PI / 180) *
      Math.cos(lat2 * Math.PI / 180) *
      Math.sin(dLon / 2) *
      Math.sin(dLon / 2);
  var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  var d = R * c;
  return d * 1000; // meters
}
function dst ( lat1 , lon1 , lat2 , lon2 ) { // generally used geo measurement function var dLat = lat2 * Math . PI / 180 - lat1 * Math . PI / 180 ; var dLon = lon2 * Math . PI / 180 - lon1 * Math . PI / 180 ; var a = Math . sin ( dLat / 2 ) * Math . sin ( dLat / 2 ) + Math . cos ( lat1 * Math . PI / 180 ) * Math . cos ( lat2 * Math . PI / 180 ) * Math . sin ( dLon / 2 ) * Math . sin ( dLon / 2 ) ; var c = 2 * Math . atan2 ( Math . sqrt ( a ) , Math . sqrt ( 1 - a ) ) ; var d = R * c ; return d * 1000 ; // meters }
Radius of earth in KM
Radius of earth in KM