pointinpolygon.js

function pointInPolygon (point, polygon){
            var i,
                j,
                c = 0,
                pointX = point.x,
                pointY = point.y;

            for (i = 0, j = polygon.length - 1, len = polygon.length; i < len; j = i++){

                if (((polygon[i].y > pointY) != (polygon[j].y > pointY)) && (pointX < (polygon[j].x - polygon[i].x) * (pointY - polygon[i].y) / (polygon[j].y - polygon[i].y) + polygon[i].x)){
                    c = !c;
                }
            }
            return c;
        }