Get distance between to geolocations in kilometers

distanceBetween.js

var distance = distanceBetween({
  lat: 59.329323,
  lng: 18.068581
}, {
  lat: 57.708870,
  lng: 11.974560
});

function getRadius(x) {
  return x * Math.PI / 180;
}

function distanceBetween(x, y) {
  var R = 6371; // Earth radius
  var dLat  = getRadius(y.lat - x.lat);
  var dLong = getRadius(y.lng - x.lng);

  var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(getRadius(x.lat)) * Math.cos(getRadius(y.lat)) * Math.sin(dLong / 2) * Math.sin(dLong / 2);
  var b = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
  var c = R * b;

  return Math.round(c)
}