Find distance between two Geographical positions

Haversine formula:

a = sin²(Δlat/2) + cos(lat1).cos(lat2).sin²(Δlong/2)
c = 2.atan2(√a, √(1−a))
d = R.c
where R is earth’s radius (mean radius = 6,371km);
note that angles need to be in radians to pass to trig functions!
JavaScript:
var R = 6371; // km
var dLat = (lat2-lat1).toRad();
var dLon = (lon2-lon1).toRad();
var lat1 = lat1.toRad();
var lat2 = lat2.toRad();

var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(lat1) * Math.cos(lat2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;

To Save the Jquery sortable data in database

<ul id="sortable" >
<li id="id1">elem 1 </li >
<li id="id2">elem 2 </li >
<li id="id3">elem 3 </li >
<li id="id4">elem 4 </li >
</ul >

$(document).ready(function(){
$('#sortable').sortable({
update: function(event, ui) {
var sortData= $(this).sortable('toArray').toString();
$.get('ajaxfilename.php', {order:sortData});
}
});
});

here sortData will get changed whenever a change is made in the Sortable