code: function(coords) {
          var i, j, area = 0;
          for (i = 0; i < coords.length; i++) {
              j = (i + 1) % coords.length;
              area += coords[i][0] * coords[j][1];
              area -= coords[j][0] * coords[i][1];
          }
          return (area < 0);
      }
docs: Returns <code>true</code> if the specified sequence of points are
  arranged in the clockwise order.