find_nearest point

gistfile1.txt

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

function find_nearest(my_position, points) {
    var lat = my_position[0];
    var lng = my_position[1];
    var R = 6371; // radius of earth in km
    var distances = [];
    var closest = null;
    for( i=0;i<points.length; i++ ) {
        var mlat = points[i][0];
        var mlng = points[i][1];
        var dLat  = rad(mlat - lat);
        var dLong = rad(mlng - lng);
        var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
            Math.cos(rad(lat)) * Math.cos(rad(lat)) * Math.sin(dLong/2) * Math.sin(dLong/2);
        var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        var d = R * c;
        distances[i] = d;
        if ( closest == -1 || d < distances[closest] ) {
            closest = i;
        }
    }
    return closest;
}

//  find_nearest( [1,2], [  [2,3], [2, 3]  ]  )