<script type="text/javascript">
var R = 6371; // km
var lat1=14.8495;
var lon1=103.495;
var lat2=14.85467;
var lon2=103.48357;
var dLat = (lat2-lat1).toRad();
var dLon = (lon2-lon1).toRad();
var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) *
Math.sin(dLon/2) * Math.sin(dLon/2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;
alert("ระยะทางคือ +d");
</script>