Leaflet Polygon Intersection algorithm

//modified from https://stackoverflow.com/questions/31790344/determine-if-a-point-reside-inside-a-leaflet-polygon

    function isPointInsideMarker(point, poly) {
        var polyPoints = poly.getLatLngs()[0];
        var x = point.lat, y = point.lng;

        var inside = false;
        for (var i = 0, j = polyPoints.length - 1; i < polyPoints.length; j = i++) {
            var xi = polyPoints[i].lat, yi = polyPoints[i].lng;
            var xj = polyPoints[j].lat, yj = polyPoints[j].lng;

            var intersect = ((yi > y) != (yj > y))
                && (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
            if (intersect) inside = !inside;
        }

        return inside;
    }