plit(',');
                for (var i=0; i<files.length; i++) {
                    if (i) query += ',';
                    query += '%22' + encodeURIComponent(files[i]) + '%22';
                }
                query += '%5D';
            }
            query += '%7D';

            const preview = document.getElementById("preview");
            preview.src = './'
                + query
                + '&embed'
                + (mapbox_token ? '&token='+mapbox_token : '')
                + (mapbox_styl