NearestLocation.js

var locations = [[37,-122],[38,-121],[39,-120]], // An array of arrays of [ lat , lng ]. You'll find the closest to target
target = [37.75,-121], // starting point
radians = function (deg) {
  return Math.PI*deg/180; // needed function not native to JavaScript's Math object
};

function getDistances (target, locations) {
    var spots = [];
    for (var i=0;i<locations.length;i++) {
        var distance = 0,
        loc = locations[i];
        with (Math) {
            distance = ( 3959 * acos( cos( radians(target[0]) ) * cos( radians( loc[0] ) ) * cos( radians( loc[1] ) - radians(target[1]) ) + sin( radians(target[0]) ) * sin( radians( loc[0] ) ) ) );
            }
        spots.push({'distance':distance,'points':loc})
    }
    return spots;
}

function sortSpots (spots) {
    return spots.sort(function(prev, next){
        return (prev.distance <= next.distance) ? -1 : 1;
    });
}

sortSpots(getDistances(target, locations)) // This returns the closest