Вот ребята и gals версии JavaScript
function distanceTo(lat1, lon1, lat2, lon2, unit) {
var rlat1 = Math.PI * lat1/180
var rlat2 = Math.PI * lat2/180
var rlon1 = Math.PI * lon1/180
var rlon2 = Math.PI * lon2/180
var theta = lon1-lon2
var rtheta = Math.PI * theta/180
var dist = Math.sin(rlat1) * Math.sin(rlat2) + Math.cos(rlat1) * Math.cos(rlat2) * Math.cos(rtheta);
dist = Math.acos(dist)
dist = dist * 180/Math.PI
dist = dist * 60 * 1.1515
if (unit=="K") { dist = dist * 1.609344 }
if (unit=="N") { dist = dist * 0.8684 }
return dist
}