Given an array of [x,y], sort the array in counter clockwise order, or specify ccw=false to sort in clockwise order.

sortCCW

var sortCCW = function(points,ccw){
  //find the centroid or average of the points
  var avg = [];
  var x = 0;
  var y = 0;

  for (var i = 0; i < points.length; i++){
    x = x + Number(points[i][0]);
    y = y + Number(points[i][1]);
  }
  avg[0] = x/points.length;
  avg[1] = y/points.length;

  //function to return the bearing between two points, center and other point
  var bearing = function(c,p){
    var lon1 = c[0];
    var lat1 = c[1];
    var lon2 = p[0];
    var lat2 = p[1];

    var dlat = lat2 - lat1;
    var dlon = lon2 - lon1;

    var b
    b = Math.atan2(dlat, dlon) * 180 / Math.PI;
    return b;
  }

  //add the bearing to each of the points as a third element in the vertex
  for (var i = 0; i < points.length; i++){
    points[i][2] = bearing(avg,points[i]);
  }

  //sort the points by bearing
  points.sort(function(a,b){
    var x = a[2];
    var y = b[2];
    return y-x;
  })

  //strip out the bearing values to return a sorted copy of the original array
  var newPoints = [];
  for(var i = 0; i < points.length; i++){
    newPoints.push([points[i][0],points[i][1]]);
  }

  //return the arrays reverse to get it CCW, unless the call overrides it with ccw=false
  if(ccw===false){
    return newPoints;
  }else{
    return newPoints.reverse();
  }
};