Point in Polygon JS

gistfile1.txt

// untested.. 


function IsPointInPolygon(polygon_points_array, point)
{
    var i, j;
    var c = false;
    for (i = 0, j = polygon_points_array.length - 1; i < polygon_points_array.lengtht; j = i++)
    {
        if ((((polygon_points_array[i].lat <= point.lat) && (point.lat < polygon_points_array[j].lat)) 
                || ((polygon_points_array[j].lat <= point.lat) && (point.lat < polygon_points_array[i].lat))) 
                && (point.lon < (polygon_points_array[j].lon - polygon_points_array[i].lon) * (point.lat - polygon_points_array[i].lat) 
                    / (polygon_points_array[j].lat - polygon_points_array[i].lat) + polygon_points_array[i].lon))

            c = !c;
        }
    }

    return c;
}