defined");
            return;
        }
        if (loadedTracks.has(trackid))
            return;
        loadedTracks.add(trackid);

        if (trackCache.has(trackid)) {
            showgeojson(trackCache.get(trackid));
        } else {
            var url = "/api/slim_geojson/" + trackid + ".geojson";
            fetch(url)
                .then(response => {
                    if (response.status === 200) {
                        return response.json();
                    } else {
                