5 * Version of this script. If the server returns a version larger than
6 * this, it is a sign we should reload to upgrade ourselves.
11 let SCRIPT_VERSION = 2021021300;
14 * The current backend URL.
19 let backend_url = "/analysis.pl";
20 let backend_hash_url = "/hash";
22 /** @type {window.ChessBoard} @private */
25 /** @type {boolean} @private */
26 let board_is_animating = false;
29 * The most recent analysis data we have from the server
30 * (about the most recent position).
34 let current_analysis_data = null;
37 * If we are displaying previous analysis or from hash, this is non-null,
38 * and will override most of current_analysis_data.
43 let displayed_analysis_data = null;
46 * Games currently in progress, if any.
58 let current_games = null;
73 /** @type {Array.<Array.<boolean>>} */
74 let occupied_by_arrows = [];
76 /** Currently displayed refutation lines (on-screen).
77 * Can either come from the current_analysis_data, displayed_analysis_data,
78 * or hash_refutation_lines.
80 let refutation_lines = [];
82 /** Refutation lines from current hash probe.
84 * If non-null, will override refutation lines from the base position.
85 * Note that these are relative to display_fen, not base_fen.
87 let hash_refutation_lines = null;
89 /** @type {!number} @private */
92 /** @type {!string} @private */
95 /** @type {number} @private */
98 /** @type {boolean} @private */
99 let truncate_display_history = true;
101 /** @type {!string|undefined} @private */
102 let highlight_from = undefined;
104 /** @type {!string|undefined} @private */
105 let highlight_to = undefined;
107 /** The HTML object of the move currently being highlighted (in red).
110 let highlighted_move = null;
112 /** Currently suggested/recommended move when dragging.
113 * @type {?{from: !string, to: !string}}
116 let recommended_move = null;
118 /** If reverse-dragging (dragging from the destination square to the
119 * source square), the destination square.
123 let reverse_dragging_from = null;
125 /** @type {?number} @private */
128 /** @type {boolean} @private */
129 let enable_sound = false;
131 /** @type {!number} @private */
135 * Our best estimate of how many milliseconds we need to add to
136 * new Date() to get the true UTC time. Calibrated against the
142 let client_clock_offset_ms = null;
144 let clock_timer = null;
146 /** The current position being analyzed, represented as a FEN string.
147 * Note that this is not necessarily the same as display_fen.
153 /** The current position on the board, represented as a FEN string.
154 * Note that board.fen() does not contain e.g. who is to play.
158 let display_fen = null;
162 * pv: Array.<string>,
165 * scores: Array<{first_move: number, score: Object}>,
166 * start_display_move_num: number
169 * "start_display_move_num" is the (half-)move number to start displaying the PV at.
170 * "score" is also evaluated at this point.
173 /** All PVs that we currently know of.
175 * Element 0 is history (or null if no history).
176 * Element 1 is current main PV, or explored line if nowhere else on the screen.
177 * All remaining elements are refutation lines (multi-PV).
179 * @type {Array.<DisplayLine>}
182 let display_lines = [];
184 /** @type {?DisplayLine} @private */
185 let current_display_line = null;
187 /** @type {boolean} @private */
188 let current_display_line_is_history = false;
190 /** @type {?number} @private */
191 let current_display_move = null;
194 * The current backend request to get main analysis (not history), if any,
195 * so that we can abort it.
197 * @type {?AbortController}
200 let current_analysis_xhr = null;
203 * The current timer to fire off a request to get main analysis (not history),
204 * if any, so that we can abort it.
209 let current_analysis_request_timer = null;
212 * The current backend request to get historic data, if any.
214 * @type {?AbortController}
217 let current_historic_xhr = null;
220 * The current backend request to get hash probes, if any, so that we can abort it.
222 * @type {?AbortController}
225 let current_hash_xhr = null;
228 * The current timer to display hash probe information (it could be waiting on the
229 * board to stop animating), if any, so that we can abort it.
234 let current_hash_display_timer = null;
236 function supports_html5_storage() {
238 return 'localStorage' in window && window['localStorage'] !== null;
244 // Make the unique token persistent so people refreshing the page won't count twice.
245 // Of course, you can never fully protect against people deliberately wanting to spam.
246 function get_unique() {
247 let use_local_storage = supports_html5_storage();
248 if (use_local_storage && window['localStorage']['unique']) {
249 return window['localStorage']['unique'];
251 let unique = Math.random();
252 if (use_local_storage) {
253 window['localStorage']['unique'] = unique;
258 function request_update() {
259 current_analysis_request_timer = null;
261 let handle_err = () => {
262 // Backend error or similar. Wait ten seconds, then try again.
263 current_analysis_request_timer = setTimeout(function() { request_update(); }, 10000);
266 current_analysis_xhr = new AbortController();
267 const signal = current_analysis_xhr.signal;
268 fetch(backend_url + "?ims=" + ims + "&unique=" + unique, { signal })
269 .then((response) => response.json().then(data => ({ok: response.ok, headers: response.headers, json: data}))) // ick
276 if (delay_ms === 0) {
277 process_update_response(obj.json, obj.headers);
279 setTimeout(function() { process_update_response(obj.json, obj.headers); }, delay_ms);
283 if (!backend_url.match(/history/)) {
285 current_analysis_request_timer = setTimeout(function() { request_update(); }, timeout);
289 if (err.name === 'AbortError') {
290 // Aborted because we are switching backends. Abandon and don't retry,
291 // because another one is already started for us.
299 document.body.style.opacity = null;
304 function process_update_response(data, headers) {
305 sync_server_clock(headers.get('Date'));
306 ims = headers.get('X-RGLM');
307 let num_viewers = headers.get('X-RGNV');
309 if (Array.isArray(data)) {
310 new_data = JSON.parse(JSON.stringify(current_analysis_data));
311 JSON_delta.patch(new_data, data);
316 let minimum_version = headers.get('X-RGMV');
317 if (minimum_version && minimum_version > SCRIPT_VERSION) {
318 // Upgrade to latest version with a force-reload.
319 location.reload(true);
322 // Verify that the PV makes sense.
324 if (new_data['pv']) {
325 let hiddenboard = new Chess(new_data['position']['fen']);
326 for (let i = 0; i < new_data['pv'].length; ++i) {
327 if (hiddenboard.move(new_data['pv'][i]) === null) {
335 possibly_play_sound(current_analysis_data, new_data);
336 current_analysis_data = new_data;
338 update_num_viewers(num_viewers);
340 console.log("Received invalid update, waiting five seconds and trying again.");
341 setTimeout(function() { location.reload(true); }, 5000);
345 function possibly_play_sound(old_data, new_data) {
349 if (old_data === null) {
352 let ding = document.getElementById('ding');
353 if (ding && ding.play) {
354 if (old_data['position'] && old_data['position']['fen'] &&
355 new_data['position'] && new_data['position']['fen'] &&
356 (old_data['position']['fen'] !== new_data['position']['fen'] ||
357 old_data['position']['move_num'] !== new_data['position']['move_num'])) {
364 * @type {!string} server_date_string
366 function sync_server_clock(server_date_string) {
367 let server_time_ms = new Date(server_date_string).getTime();
368 let client_time_ms = new Date().getTime();
369 let estimated_offset_ms = server_time_ms - client_time_ms;
371 // In order not to let the noise move us too much back and forth
372 // (the server only has one-second resolution anyway), we only
373 // change an existing skew if we are at least five seconds off.
374 if (client_clock_offset_ms === null ||
375 Math.abs(estimated_offset_ms - client_clock_offset_ms) > 5000) {
376 client_clock_offset_ms = estimated_offset_ms;
380 function clear_arrows() {
381 for (let i = 0; i < arrows.length; ++i) {
383 arrows[i].svg.remove();
384 delete arrows[i].svg;
389 occupied_by_arrows = [];
390 for (let y = 0; y < 8; ++y) {
391 occupied_by_arrows.push([false, false, false, false, false, false, false, false]);
395 function redraw_arrows() {
396 for (let i = 0; i < arrows.length; ++i) {
397 position_arrow(arrows[i]);
401 /** @param {!number} x
414 /** See if drawing this arrow on the board would cause unduly amount of confusion.
415 * @param {!string} from The square the arrow is from (e.g. e4).
416 * @param {!string} to The square the arrow is to (e.g. e4).
419 function interfering_arrow(from, to) {
420 let from_col = from.charCodeAt(0) - "a1".charCodeAt(0);
421 let from_row = from.charCodeAt(1) - "a1".charCodeAt(1);
422 let to_col = to.charCodeAt(0) - "a1".charCodeAt(0);
423 let to_row = to.charCodeAt(1) - "a1".charCodeAt(1);
425 occupied_by_arrows[from_row][from_col] = true;
427 // Knight move: Just check that we haven't been at the destination before.
428 if ((Math.abs(to_col - from_col) == 2 && Math.abs(to_row - from_row) == 1) ||
429 (Math.abs(to_col - from_col) == 1 && Math.abs(to_row - from_row) == 2)) {
430 return occupied_by_arrows[to_row][to_col];
433 // Sliding piece: Check if anything except the from-square is seen before.
434 let dx = sign(to_col - from_col);
435 let dy = sign(to_row - from_row);
441 if (occupied_by_arrows[y][x]) {
444 occupied_by_arrows[y][x] = true;
445 } while (x != to_col || y != to_row);
450 /** Find a point along the coordinate system given by the given line,
451 * <t> units forward from the start of the line, <u> units to the right of it.
452 * @param {!number} x1
453 * @param {!number} x2
454 * @param {!number} y1
455 * @param {!number} y2
458 * @return {!string} The point in "x y" form, suitable for SVG paths.
460 function point_from_start(x1, y1, x2, y2, t, u) {
464 let norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
468 let x = x1 + dx * t + dy * u;
469 let y = y1 + dy * t - dx * u;
473 /** Find a point along the coordinate system given by the given line,
474 * <t> units forward from the end of the line, <u> units to the right of it.
475 * @param {!number} x1
476 * @param {!number} x2
477 * @param {!number} y1
478 * @param {!number} y2
481 * @return {!string} The point in "x y" form, suitable for SVG paths.
483 function point_from_end(x1, y1, x2, y2, t, u) {
487 let norm = 1.0 / Math.sqrt(dx * dx + dy * dy);
491 let x = x2 + dx * t + dy * u;
492 let y = y2 + dy * t - dx * u;
496 function position_arrow(arrow) {
498 if (arrow.svg.parentElement) {
499 arrow.svg.parentElement.removeChild(arrow.svg);
503 if (current_display_line !== null && !current_display_line_is_history) {
507 // We always draw as if the board is 400x400, the viewBox will adjust that for us
508 let line_width = arrow.line_width;
509 let arrow_size = arrow.arrow_size;
511 let square_width = 400 / 8;
512 let from_y, to_y, from_x, to_x;
513 if (board.orientation() === 'black') {
514 from_y = (arrow.from_row + 0.5)*square_width;
515 to_y = (arrow.to_row + 0.5)*square_width;
516 from_x = (7 - arrow.from_col + 0.5)*square_width;
517 to_x = (7 - arrow.to_col + 0.5)*square_width;
519 from_y = (7 - arrow.from_row + 0.5)*square_width;
520 to_y = (7 - arrow.to_row + 0.5)*square_width;
521 from_x = (arrow.from_col + 0.5)*square_width;
522 to_x = (arrow.to_col + 0.5)*square_width;
525 let SVG_NS = "http://www.w3.org/2000/svg";
526 let XHTML_NS = "http://www.w3.org/1999/xhtml";
527 let svg = document.createElementNS(SVG_NS, "svg");
528 svg.setAttribute("width", "100%");
529 svg.setAttribute("height", "100%");
530 svg.setAttribute("viewBox", "0 0 400 400");
531 svg.setAttribute("version", "1.1");
532 svg.setAttribute("class", "c1");
533 svg.setAttribute("xmlns", XHTML_NS);
541 let outline = document.createElementNS(SVG_NS, "path");
542 outline.setAttribute("d", "M " + point_from_start(x1, y1, x2, y2, arrow_size / 2, 0) + " L " + point_from_end(x1, y1, x2, y2, -arrow_size / 2, 0));
543 outline.setAttribute("xmlns", XHTML_NS);
544 outline.setAttribute("stroke", "#666");
545 outline.setAttribute("stroke-width", line_width + 2);
546 outline.setAttribute("fill", "none");
547 svg.appendChild(outline);
549 let path = document.createElementNS(SVG_NS, "path");
550 path.setAttribute("d", "M " + point_from_start(x1, y1, x2, y2, arrow_size / 2, 0) + " L " + point_from_end(x1, y1, x2, y2, -arrow_size / 2, 0));
551 path.setAttribute("xmlns", XHTML_NS);
552 path.setAttribute("stroke", arrow.fg_color);
553 path.setAttribute("stroke-width", line_width);
554 path.setAttribute("fill", "none");
555 svg.appendChild(path);
557 // Then the arrow head.
558 let head = document.createElementNS(SVG_NS, "path");
559 head.setAttribute("d",
560 "M " + point_from_end(x1, y1, x2, y2, 0, 0) +
561 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, -arrow_size / 2) +
562 " L " + point_from_end(x1, y1, x2, y2, -arrow_size * .623, 0.0) +
563 " L " + point_from_end(x1, y1, x2, y2, -arrow_size, arrow_size / 2) +
564 " L " + point_from_end(x1, y1, x2, y2, 0, 0));
565 head.setAttribute("xmlns", XHTML_NS);
566 head.setAttribute("stroke", "#000");
567 head.setAttribute("stroke-width", "1");
568 head.setAttribute("fill", arrow.fg_color);
569 svg.appendChild(head);
571 svg.style.position = 'absolute';
572 svg.style.top = '0px'; /* Border for .board-b72b1. */
573 svg.style.left = '0px';
574 svg.style.pointerEvents = 'none';
575 document.getElementById('board').appendChild(svg);
580 * @param {!string} from_square
581 * @param {!string} to_square
582 * @param {!string} fg_color
583 * @param {number} line_width
584 * @param {number} arrow_size
586 function create_arrow(from_square, to_square, fg_color, line_width, arrow_size) {
587 let from_col = from_square.charCodeAt(0) - "a1".charCodeAt(0);
588 let from_row = from_square.charCodeAt(1) - "a1".charCodeAt(1);
589 let to_col = to_square.charCodeAt(0) - "a1".charCodeAt(0);
590 let to_row = to_square.charCodeAt(1) - "a1".charCodeAt(1);
598 line_width: line_width,
599 arrow_size: arrow_size,
603 position_arrow(arrow);
607 function compare_by_score(refutation_lines, invert, a, b) {
608 let sa = compute_score_sort_key(refutation_lines[b]['score'], refutation_lines[b]['depth'], invert);
609 let sb = compute_score_sort_key(refutation_lines[a]['score'], refutation_lines[a]['depth'], invert);
614 * Fake multi-PV using the refutation lines. Find all “relevant” moves,
615 * sorted by quality, descending.
617 * @param {!Object} data
618 * @param {number} margin The maximum number of centipawns worse than the
619 * best move can be and still be included.
620 * @param {boolean} invert Whether black is to play.
621 * @return {Array.<string>} The FEN representation (e.g. Ne4) of all
622 * moves, in score order.
624 function find_nonstupid_moves(data, margin, invert) {
625 // First of all, if there are any moves that are more than 0.5 ahead of
626 // the primary move, the refutation lines are probably bunk, so just
628 let best_score = undefined;
629 let pv_score = undefined;
630 for (let move in data['refutation_lines']) {
631 let line = data['refutation_lines'][move];
632 let score = compute_score_sort_key(line['score'], line['depth'], invert);
633 if (move == data['pv'][0]) {
636 if (best_score === undefined || score > best_score) {
639 if (line['depth'] < 8) {
644 if (best_score - pv_score > 50) {
648 // Now find all moves that are within “margin” of the best score.
649 // The PV move will always be first.
651 for (let move in data['refutation_lines']) {
652 let line = data['refutation_lines'][move];
653 let score = compute_score_sort_key(line['score'], line['depth'], invert);
654 if (move != data['pv'][0] && best_score - score <= margin) {
658 moves = moves.sort(function(a, b) { return compare_by_score(data['refutation_lines'], data['position']['toplay'] === 'B', a, b) });
659 moves.unshift(data['pv'][0]);
668 function thousands(x) {
669 return String(x).split('').reverse().join('').replace(/(\d{3}\B)/g, '$1,').split('').reverse().join('');
673 * @param {!string} start_fen
674 * @param {Array.<string>} pv
675 * @param {number} move_num
676 * @param {!string} toplay
677 * @param {Array<{ first_move: integer, score: Object }>} scores
678 * @param {number} start_display_move_num
679 * @param {number=} opt_limit
680 * @param {boolean=} opt_showlast
682 function add_pv(start_fen, pv, move_num, toplay, scores, start_display_move_num, opt_limit, opt_showlast) {
684 start_fen: start_fen,
686 move_num: parseInt(move_num),
689 start_display_move_num: start_display_move_num
691 let splicepos = null;
692 if (scores !== null && scores.length >= 1 &&
693 scores[scores.length - 1].score !== undefined &&
694 scores[scores.length - 1].score !== null &&
695 (scores[scores.length - 1].score[0] === 'T' ||
696 scores[scores.length - 1].score[0] === 't')) {
697 splicepos = scores[scores.length - 1].score[1];
699 return print_pv(display_lines.length - 1, splicepos, opt_limit, opt_showlast);
703 * @param {number} line_num
704 * @param {?number} splicepos If non-null, where the tablebase-spliced portion of the TB starts.
705 * @param {number=} opt_limit If set, show at most this number of moves.
706 * @param {boolean=} opt_showlast If limit is set, show the last moves instead of the first ones.
708 function print_pv(line_num, splicepos, opt_limit, opt_showlast) {
709 let display_line = display_lines[line_num];
710 let pv = display_line.pv;
711 let move_num = display_line.move_num;
712 let toplay = display_line.toplay;
714 // Truncate PV at the start if needed.
715 let start_display_move_num = display_line.start_display_move_num;
716 if (start_display_move_num > 0) {
717 pv = pv.slice(start_display_move_num);
718 let to_add = start_display_move_num;
719 if (toplay === 'B') {
724 if (to_add % 2 == 1) {
728 move_num += to_add / 2;
729 if (splicepos !== null && splicepos > 0) {
734 let ret = document.createDocumentFragment();
737 if (opt_limit && opt_showlast && pv.length > opt_limit) {
738 // Truncate the PV at the beginning (instead of at the end).
739 // We assume here that toplay is 'W'. We also assume that if
740 // opt_showlast is set, then it is the history, and thus,
741 // the UI should be to expand the history.
742 ret.appendChild(document.createTextNode('('));
743 let link = document.createElement('a');
744 link.className = 'move';
745 link.href = 'javascript:collapse_history(false)';
746 link.textContent = '…';
747 ret.appendChild(link);
748 ret.appendChild(document.createTextNode(') '));
749 i = pv.length - opt_limit;
754 } else if (toplay == 'B' && pv.length > 0) {
755 ret.appendChild(document.createTextNode(move_num + '. … '));
757 for (; i < pv.length; ++i) {
758 let link = document.createElement('a');
759 link.className = 'move';
760 link.setAttribute('id', 'automove' + line_num + '-' + i);
761 link.textContent = pv[i];
762 link.href = 'javascript:show_line(' + line_num + ', ' + i + ');';
763 if (splicepos === i) {
764 ret.appendChild(document.createTextNode('(TB: '));
768 if (toplay == 'B' && i == 0) {
771 } else if (toplay == 'W') {
772 if (i > opt_limit && !opt_showlast) {
774 ret.appendChild(document.createTextNode(')'));
776 ret.appendChild(document.createTextNode(' (…)'));
779 ret.appendChild(document.createTextNode(' ' + move_num + '. '));
783 ret.appendChild(document.createTextNode(' '));
786 ret.appendChild(link);
789 ret.appendChild(document.createTextNode(')'));
794 /** Update the highlighted to/from squares on the board.
795 * Based on the global "highlight_from" and "highlight_to" letiables.
797 function update_board_highlight() {
798 document.getElementById("board").querySelectorAll('.square-55d63').forEach((square) => square.classList.remove('nonuglyhighlight'));
799 if ((current_display_line === null || current_display_line_is_history) &&
800 highlight_from !== undefined && highlight_to !== undefined) {
801 document.getElementById("board").querySelector('.square-' + highlight_from).classList.add('nonuglyhighlight');
802 document.getElementById("board").querySelector('.square-' + highlight_to).classList.add('nonuglyhighlight');
806 function update_history() {
807 let history = document.getElementById('history');
808 if (display_lines[0] === null || display_lines[0].pv.length == 0) {
809 history.textContent = 'No history';
810 } else if (truncate_display_history) {
811 history.replaceChildren(print_pv(0, null, 8, true));
813 history.textContent = '(';
814 let link = document.createElement('a');
815 link.className = 'move';
816 link.href = 'javascript:collapse_history(true)';
817 link.textContent = 'collapse';
818 history.appendChild(link);
819 history.appendChild(document.createTextNode(') '));
820 history.append(print_pv(0, null));
825 * @param {!boolean} truncate_history
827 function collapse_history(truncate_history) {
828 truncate_display_history = truncate_history;
831 window['collapse_history'] = collapse_history;
833 /** Update the HTML display of multi-PV from the global "refutation_lines".
835 * Also recreates the global "display_lines".
837 function update_refutation_lines() {
838 if (base_fen === null) {
841 if (display_lines.length > 2) {
842 // Truncate so that only the history and PV is left.
843 display_lines = [ display_lines[0], display_lines[1] ];
845 let tbl = document.getElementById("refutationlines");
846 tbl.replaceChildren();
848 if (display_lines.length < 2) {
849 // Update the move highlight, as we've rewritten all the HTML.
850 update_move_highlight();
854 // Find out where the lines start from.
856 let base_scores = display_lines[1].scores;
857 let start_display_move_num = 0;
858 if (hash_refutation_lines) {
859 base_line = current_display_line.pv.slice(0, current_display_move + 1);
860 base_scores = current_display_line.scores;
861 start_display_move_num = base_line.length;
865 for (let move in refutation_lines) {
869 let invert = (toplay === 'B');
870 if (current_display_line && current_display_move % 2 == 0 && !current_display_line_is_history) {
873 moves = moves.sort(function(a, b) { return compare_by_score(refutation_lines, invert, a, b) });
874 for (let i = 0; i < moves.length; ++i) {
875 let line = refutation_lines[moves[i]];
877 let tr = document.createElement("tr");
879 let move_td = document.createElement("td");
880 tr.appendChild(move_td);
881 move_td.classList.add("move");
883 let scores = base_scores.concat([{ first_move: start_display_move_num, score: line['score'] }]);
885 if (line['pv'].length == 0) {
886 // Not found, so just make a one-move PV.
887 let link = document.createElement('a');
888 link.className = 'move';
889 link.href = 'javascript:show_line(' + display_lines.length + ', ' + 0 + ')';
890 link.textContent = line['move'];
891 move_td.replaceChildren(link);
893 let score_td = document.createElement("td");
894 score_td.classList.add("score");
895 score_td.textContent = "—";
896 tr.appendChild(score_td);
898 let depth_td = document.createElement("td");
899 tr.appendChild(depth_td);
900 depth_td.classList.add("depth");
901 depth_td.textContent = "—";
903 let pv_td = document.createElement("td");
904 tr.appendChild(pv_td);
905 pv_td.classList.add("pv");
906 pv_td.append(add_pv(base_fen, base_line.concat([ line['move'] ]), move_num, toplay, scores, start_display_move_num));
912 let move_link = document.createElement("a");
913 move_link.classList.add("move");
914 move_link.setAttribute("href", "javascript:show_line(" + display_lines.length + ", 0)");
915 move_link.textContent = line['move'];
916 move_td.appendChild(move_link);
918 let score_td = document.createElement("td");
919 tr.appendChild(score_td);
920 score_td.classList.add("score");
921 score_td.textContent = format_short_score(line['score']);
923 let depth_td = document.createElement("td");
924 tr.appendChild(depth_td);
925 depth_td.classList.add("depth");
926 if (line['depth'] && line['depth'] >= 0) {
927 depth_td.textContent = "d" + line['depth'];
929 depth_td.textContent = "—";
932 let pv_td = document.createElement("td");
933 tr.appendChild(pv_td);
934 pv_td.classList.add("pv");
935 pv_td.append(add_pv(base_fen, base_line.concat(line['pv']), move_num, toplay, scores, start_display_move_num, 10));
940 // Update the move highlight, as we've rewritten all the HTML.
941 update_move_highlight();
945 * Create a Chess.js board object, containing the given position plus the given moves,
946 * up to the given limit.
948 * @param {?string} fen
949 * @param {Array.<string>} moves
950 * @param {number} last_move
952 function chess_from(fen, moves, last_move) {
953 let hiddenboard = new Chess();
954 if (fen !== null && fen !== undefined) {
955 hiddenboard.load(fen);
957 for (let i = 0; i <= last_move; ++i) {
958 if (moves[i] === '0-0') {
959 hiddenboard.move('O-O');
960 } else if (moves[i] === '0-0-0') {
961 hiddenboard.move('O-O-O');
963 hiddenboard.move(moves[i]);
969 function update_game_list(games) {
970 document.getElementById("games").textContent = "";
971 if (games === null) {
975 let games_div = document.getElementById('games');
976 for (let game_num = 0; game_num < games.length; ++game_num) {
977 let game = games[game_num];
978 let game_span = document.createElement("span");
979 game_span.setAttribute("class", "game");
981 let game_name = document.createTextNode(game['name']);
982 if (game['url'] === backend_url) {
984 game_span.appendChild(game_name);
986 if (current_analysis_data && current_analysis_data['position']) {
988 if (current_analysis_data['position']['result']) {
989 score = " (" + current_analysis_data['position']['result'] + ")";
991 score = " (" + format_short_score(current_analysis_data['score']) + ")";
993 game_span.appendChild(document.createTextNode(score));
997 let game_a = document.createElement("a");
998 game_a.setAttribute("href", "#" + game['id']);
999 game_a.appendChild(game_name);
1000 game_span.appendChild(game_a);
1003 if (game['result']) {
1004 score = " (" + game['result'] + ")";
1006 score = " (" + format_short_score(game['score']) + ")";
1008 game_span.appendChild(document.createTextNode(score));
1011 games_div.appendChild(game_span);
1016 * Try to find a running game that matches with the current hash,
1017 * and switch to it if we're not already displaying it.
1019 function possibly_switch_game_from_hash() {
1020 let history_match = window.location.hash.match(/^#history=([a-zA-Z0-9_-]+)/);
1021 if (history_match !== null) {
1022 let game_id = history_match[1];
1024 url: '/history/' + game_id + '.json',
1026 id: 'history=' + game_id
1028 switch_backend(fake_game);
1032 if (current_games === null) {
1036 let hash = window.location.hash.replace(/^#/,'');
1037 for (let i = 0; i < current_games.length; ++i) {
1038 if (current_games[i]['id'] === hash) {
1039 if (backend_url !== current_games[i]['url']) {
1040 switch_backend(current_games[i]);
1048 * If this is a Chess960 castling which doesn't move the king,
1049 * move the rook instead.
1051 function patch_move(move) {
1052 if (move === null) return null;
1053 if (move.from !== move.to) return move;
1055 let f = move.rook_sq & 15;
1056 let r = move.rook_sq >> 4;
1057 let from = ('abcdefgh'.substring(f,f+1) + '87654321'.substring(r,r+1));
1060 if (move.to === 'g1') {
1062 } else if (move.to === 'g8') {
1064 } else if (move.to === 'b1') {
1066 } else if (move.to === 'b8') {
1070 return { from: from, to: to };
1073 /** Update all the HTML on the page, based on current global state.
1075 function update_board() {
1076 document.body.style.opacity = null;
1078 let data = displayed_analysis_data || current_analysis_data;
1079 let current_data = current_analysis_data; // Convenience alias.
1083 // Print the history. This is pretty much the only thing that's
1084 // unconditionally taken from current_data (we're not interested in
1085 // historic history).
1086 if (current_data['position']['history']) {
1087 let start = (current_data['position'] && current_data['position']['start_fen']) ? current_data['position']['start_fen'] : 'start';
1088 add_pv(start, current_data['position']['history'], 1, 'W', null, 0, 8, true);
1090 display_lines.push(null);
1094 // Games currently in progress, if any.
1095 if (current_data['games']) {
1096 current_games = current_data['games'];
1097 possibly_switch_game_from_hash();
1099 current_games = null;
1101 update_game_list(current_games);
1103 // The headline. Names are always fetched from current_data;
1104 // the rest can depend a bit.
1107 current_data['position']['player_w'] && current_data['position']['player_b']) {
1108 headline = current_data['position']['player_w'] + '–' +
1109 current_data['position']['player_b'] + ', analysis';
1111 headline = 'Analysis';
1114 // Credits, where applicable. Note that we don't want the footer to change a lot
1115 // when e.g. viewing history, so if any of these changed during the game,
1116 // use the current one still.
1117 if (current_data['using_lomonosov']) {
1118 document.getElementById("lomonosov").style.display = null;
1120 document.getElementById("lomonosov").style.display = 'none';
1123 // Credits: The engine name/version.
1124 if (current_data['engine'] && current_data['engine']['name'] !== null) {
1125 document.getElementById("engineid").textContent = current_data['engine']['name'];
1128 // Credits: The engine URL.
1129 if (current_data['engine'] && current_data['engine']['url']) {
1130 document.getElementById("engineid").setAttribute("href", current_data['engine']['url']);
1132 document.getElementById("engineid").removeAttribute("href");
1135 // Credits: Engine details.
1136 if (current_data['engine'] && current_data['engine']['details']) {
1137 document.getElementById("enginedetails").textContent = " (" + current_data['engine']['details'] + ")";
1139 document.getElementById("enginedetails").textContent = "";
1142 // Credits: Move source, possibly with URL.
1143 if (current_data['move_source'] && current_data['move_source_url']) {
1144 document.getElementById("movesource").textContent = "Moves provided by ";
1145 let movesource_a = document.createElement("a");
1146 movesource_a.setAttribute("href", current_data['move_source_url']);
1147 let movesource_text = document.createTextNode(current_data['move_source']);
1148 movesource_a.appendChild(movesource_text);
1149 let movesource_period = document.createTextNode(".");
1150 document.getElementById("movesource").appendChild(movesource_a);
1151 document.getElementById("movesource").appendChild(movesource_period);
1152 } else if (current_data['move_source']) {
1153 document.getElementById("movesource").textContent = "Moves provided by " + current_data['move_source'] + ".";
1155 document.getElementById("movesource").textContent = "";
1159 if (displayed_analysis_data) {
1160 // Displaying some non-current position, pick out the last move
1161 // from the history. This will work even if the fetch failed.
1162 if (current_display_move !== -1) {
1163 last_move = format_halfmove_with_number(
1164 current_display_line.pv[current_display_move],
1165 current_display_move);
1166 headline += ' after ' + last_move;
1168 } else if (data['position']['last_move'] !== 'none') {
1169 // Find the previous move.
1170 let previous_move_num, previous_toplay;
1171 if (data['position']['toplay'] == 'B') {
1172 previous_move_num = data['position']['move_num'];
1173 previous_toplay = 'W';
1175 previous_move_num = data['position']['move_num'] - 1;
1176 previous_toplay = 'B';
1179 last_move = format_move_with_number(
1180 data['position']['last_move'],
1182 previous_toplay == 'W');
1183 headline += ' after ' + last_move;
1187 document.getElementById("headline").textContent = headline;
1189 // The <title> contains a very brief headline.
1190 let title_elems = [];
1191 if (data['position'] && data['position']['result']) {
1192 title_elems.push(data['position']['result']);
1193 } else if (data['score']) {
1194 title_elems.push(format_short_score(data['score']));
1196 if (last_move !== null) {
1197 title_elems.push(last_move);
1200 if (title_elems.length != 0) {
1201 document.title = '(' + title_elems.join(', ') + ') analysis.sesse.net';
1203 document.title = 'analysis.sesse.net';
1206 // The last move (shown by highlighting the from and to squares).
1207 if (data['position'] && data['position']['last_move_uci']) {
1208 highlight_from = data['position']['last_move_uci'].substr(0, 2);
1209 highlight_to = data['position']['last_move_uci'].substr(2, 2);
1210 } else if (current_display_line_is_history && current_display_line && current_display_move >= 0) {
1211 // We don't have historic analysis for this position, but we
1212 // can reconstruct what the last move was by just replaying
1214 let position = (data['position'] && data['position']['start_fen']) ? data['position']['start_fen'] : null;
1215 let hiddenboard = chess_from(position, current_display_line.pv, current_display_move);
1216 let moves = hiddenboard.history({ verbose: true });
1217 last_move = moves.pop();
1218 highlight_from = last_move.from;
1219 highlight_to = last_move.to;
1221 highlight_from = highlight_to = undefined;
1223 update_board_highlight();
1225 if (data['failed']) {
1226 document.getElementById("score").textContent = "No analysis for this move";
1227 document.getElementById("pvtitle").textContent = "PV:";
1228 document.getElementById("pv").replaceChildren();
1229 document.getElementById("searchstats").textContent = " ";
1230 document.getElementById("refutationlines").replaceChildren();
1231 document.getElementById("whiteclock").replaceChildren();
1232 document.getElementById("blackclock").replaceChildren();
1233 refutation_lines = [];
1234 update_refutation_lines();
1236 update_displayed_line();
1237 update_move_highlight();
1241 if (clock_timer !== null) {
1242 clearTimeout(clock_timer);
1247 if (current_display_line && !current_display_line_is_history) {
1249 if (current_display_line.scores && current_display_line.scores.length > 0) {
1250 for (let i = 0; i < current_display_line.scores.length; ++i) {
1251 if (current_display_move < current_display_line.scores[i].first_move) {
1254 score = current_display_line.scores[i].score;
1258 document.getElementById("score").textContent = format_long_score(score);
1260 document.getElementById("score").textContent = "No score for this line";
1262 } else if (data['score']) {
1263 document.getElementById("score").textContent = format_long_score(data['score']);
1266 // The search stats.
1267 if (data['searchstats']) {
1268 document.getElementById("searchstats").textContent = data['searchstats'];
1269 } else if (data['tablebase'] == 1) {
1270 document.getElementById("searchstats").textContent = "Tablebase result";
1271 } else if (data['nodes'] && data['nps'] && data['depth']) {
1272 let stats = thousands(data['nodes']) + ' nodes, ' + thousands(data['nps']) + ' nodes/sec, depth ' + data['depth'] + ' ply';
1273 if (data['seldepth']) {
1274 stats += ' (' + data['seldepth'] + ' selective)';
1276 if (data['tbhits'] && data['tbhits'] > 0) {
1277 if (data['tbhits'] == 1) {
1278 stats += ', one Syzygy hit';
1280 stats += ', ' + thousands(data['tbhits']) + ' Syzygy hits';
1284 document.getElementById("searchstats").textContent = stats;
1286 document.getElementById("searchstats").textContent = "";
1289 // Update the board itself.
1290 base_fen = data['position']['fen'];
1291 update_displayed_line();
1294 document.getElementById("pvtitle").textContent = "PV:";
1296 let scores = [{ first_move: -1, score: data['score'] }];
1297 document.getElementById("pv").replaceChildren(add_pv(data['position']['fen'], data['pv'], data['position']['move_num'], data['position']['toplay'], scores, 0));
1299 // Update the PV arrow.
1301 if (data['pv'].length >= 1) {
1302 let hiddenboard = new Chess(base_fen);
1304 // draw a continuation arrow as long as it's the same piece
1306 for (let i = 0; i < data['pv'].length; i += 2) {
1307 let move = patch_move(hiddenboard.move(data['pv'][i]));
1309 if ((i >= 2 && move.from != last_to) ||
1310 interfering_arrow(move.from, move.to)) {
1313 create_arrow(move.from, move.to, '#f66', 6, 20);
1315 hiddenboard.move(data['pv'][i + 1]); // To keep continuity.
1318 let alt_moves = find_nonstupid_moves(data, 30, data['position']['toplay'] === 'B');
1319 for (let i = 1; i < alt_moves.length && i < 3; ++i) {
1320 hiddenboard = new Chess(base_fen);
1321 let move = patch_move(hiddenboard.move(alt_moves[i]));
1322 if (move !== null) {
1323 create_arrow(move.from, move.to, '#f66', 1, 10);
1328 // See if all semi-reasonable moves have only one possible response.
1329 if (data['pv'].length >= 2) {
1330 let nonstupid_moves = find_nonstupid_moves(data, 300, data['position']['toplay'] === 'B');
1331 let hiddenboard = new Chess(base_fen);
1332 hiddenboard.move(data['pv'][0]);
1333 let response = hiddenboard.move(data['pv'][1]);
1334 for (let i = 0; i < nonstupid_moves.length; ++i) {
1335 if (nonstupid_moves[i] == data['pv'][0]) {
1336 // ignore the PV move for refutation lines.
1339 if (!data['refutation_lines'] ||
1340 !data['refutation_lines'][nonstupid_moves[i]] ||
1341 !data['refutation_lines'][nonstupid_moves[i]]['pv'] ||
1342 data['refutation_lines'][nonstupid_moves[i]]['pv'].length < 2) {
1343 // Incomplete PV, abort.
1344 response = undefined;
1347 let line = data['refutation_lines'][nonstupid_moves[i]];
1348 hiddenboard = new Chess(base_fen);
1349 hiddenboard.move(line['pv'][0]);
1350 let this_response = hiddenboard.move(line['pv'][1]);
1351 if (this_response === null) {
1352 console.log("BUG: ", i);
1354 console.log(line['pv']);
1356 if (response.from !== this_response.from || response.to !== this_response.to) {
1357 // Different response depending on lines, abort.
1358 response = undefined;
1363 if (nonstupid_moves.length > 0 && response !== undefined) {
1364 create_arrow(response.from, response.to, '#66f', 6, 20);
1368 // Update the refutation lines.
1369 base_fen = data['position']['fen'];
1370 move_num = parseInt(data['position']['move_num']);
1371 toplay = data['position']['toplay'];
1372 refutation_lines = hash_refutation_lines || data['refutation_lines'];
1373 update_refutation_lines();
1375 // Update the sparkline last, since its size depends on how everything else reflowed.
1376 update_sparkline(data);
1379 function update_sparkline(data) {
1380 let scorespark = document.getElementById('scoresparkcontainer');
1381 scorespark.textContent = '';
1382 if (data && data['score_history']) {
1383 let first_move_num = undefined;
1384 for (let halfmove_num in data['score_history']) {
1385 halfmove_num = parseInt(halfmove_num);
1386 if (first_move_num === undefined || halfmove_num < first_move_num) {
1387 first_move_num = halfmove_num;
1390 if (first_move_num !== undefined) {
1391 let last_move_num = data['position']['move_num'] * 2 - 3;
1392 if (data['position']['toplay'] === 'B') {
1396 // Possibly truncate some moves if we don't have enough width.
1397 let max_moves = Math.floor(scorespark.getBoundingClientRect().width / 5) - 3;
1398 if (last_move_num - first_move_num > max_moves) {
1399 first_move_num = last_move_num - max_moves;
1404 let last_score = null;
1406 for (let halfmove_num = first_move_num; halfmove_num <= last_move_num; ++halfmove_num) {
1407 if (data['score_history'][halfmove_num]) {
1408 let score = compute_plot_score(data['score_history'][halfmove_num]);
1410 if (score < min_score) min_score = score;
1411 if (score > max_score) max_score = score;
1413 scores.push(last_score);
1415 if (data['score']) {
1416 let score = compute_plot_score(data['score']);
1418 if (score < min_score) min_score = score;
1419 if (score > max_score) max_score = score;
1421 if (max_score - min_score < 100) {
1422 if (Math.abs(max_score) >= Math.abs(min_score)) {
1423 max_score = min_score + 100;
1425 min_score = max_score - 100;
1429 const h = scorespark.getBoundingClientRect().height;
1431 let base_y = h - h * min_score / (min_score - max_score);
1432 for (let i = 0; i < scores.length; ++i) {
1433 let rect = document.createElementNS('http://www.w3.org/2000/svg', 'rect');
1434 //rect.setAttributeNS(null, 'stroke', "#000000");
1435 rect.setAttributeNS(null, 'x', i * 5)
1436 rect.setAttributeNS(null, 'width', 4);
1437 let extent = scores[i] * h / (max_score - min_score);
1438 if (extent > 0 && extent < 1) {
1440 } else if (extent < 0 && extent > -1) {
1445 if (scores[i] === 0) {
1446 color = [0.5, 0.5, 0.5];
1447 rect.setAttributeNS(null, 'y', base_y);
1448 rect.setAttributeNS(null, 'height', 1);
1449 } else if (scores[i] > 0) {
1450 color = [0.2, 0.4, 0.8];
1451 rect.setAttributeNS(null, 'y', base_y - extent);
1452 rect.setAttributeNS(null, 'height', extent + 1);
1454 color = [1.0, 0.267, 0.267];
1455 rect.setAttributeNS(null, 'y', base_y);
1456 rect.setAttributeNS(null, 'height', -extent + 1);
1458 let hlcolor = [color[0], color[1], color[2]];
1459 if (scores[i] !== 0) {
1460 hlcolor[0] = Math.min(hlcolor[0] * 1.4, 1.0);
1461 hlcolor[1] = Math.min(hlcolor[1] * 1.4, 1.0);
1462 hlcolor[2] = Math.min(hlcolor[2] * 1.4, 1.0);
1464 rect.style.fill = 'rgb(' + color[0]*100.0 + '%, ' + color[1]*100.0 + '%, ' + color[2]*100.0 + '%)';
1466 // score_history contains the Nth _position_, but format_tooltip
1467 // wants to format the Nth _move_; thus the -1.
1468 const tooltip = format_tooltip(data, i + first_move_num - 1);
1469 rect.addEventListener('mouseenter', (e) => draw_hover(e, hlcolor, tooltip));
1470 rect.addEventListener('mousemove', (e) => draw_hover(e, hlcolor, tooltip));
1471 rect.addEventListener('mouseleave', (e) => hide_hover(e, color));
1472 rect.addEventListener('click', (e) => { hide_hover(e, color); show_line(0, i + first_move_num - 1) });
1473 scorespark.appendChild(rect);
1479 function draw_hover(e, color, tooltip) {
1480 e.target.style.fill = 'rgb(' + color[0]*100.0 + '%, ' + color[1]*100.0 + '%, ' + color[2]*100.0 + '%)';
1482 let hover = document.getElementById('sparklinehover');
1483 hover.textContent = tooltip;
1484 hover.style.display = 'initial';
1486 let left = Math.max(e.pageX + 10, window.pageXOffset);
1487 let top = Math.max(e.pageY - hover.getBoundingClientRect().height, window.pageYOffset);
1488 left = Math.min(left, window.pageXOffset + document.documentElement.clientWidth - hover.getBoundingClientRect().width);
1490 hover.style.left = left + 'px';
1491 hover.style.top = top + 'px';
1494 function hide_hover(e, color) {
1495 e.target.style.fill = 'rgb(' + color[0]*100.0 + '%, ' + color[1]*100.0 + '%, ' + color[2]*100.0 + '%)';
1496 document.getElementById('sparklinehover').style.display = 'none';
1500 * @param {number} num_viewers
1502 function update_num_viewers(num_viewers) {
1504 if (num_viewers === null) {
1506 } else if (num_viewers == 1) {
1507 text = "You are the only current viewer";
1509 text = num_viewers + " current viewers";
1511 if (display_fen !== null) {
1512 let counter = Math.floor(display_fen.split(" ")[4] / 2);
1513 if (counter >= 20) {
1514 text = text.replace("current ", "");
1515 text += " | 50-move rule: " + counter;
1518 document.getElementById("numviewers").textContent = text;
1521 function update_clock() {
1524 let data = displayed_analysis_data || current_analysis_data;
1527 if (data['position']) {
1528 let result = data['position']['result'];
1529 if (result === '1-0') {
1530 document.getElementById("whiteclock").textContent = "1";
1531 document.getElementById("blackclock").textContent = "0";
1532 document.getElementById("whiteclock").classList.remove("running-clock");
1533 document.getElementById("blackclock").classList.remove("running-clock");
1536 if (result === '1/2-1/2') {
1537 document.getElementById("whiteclock").textContent = "1/2";
1538 document.getElementById("blackclock").textContent = "1/2";
1539 document.getElementById("whiteclock").classList.remove("running-clock");
1540 document.getElementById("blackclock").classList.remove("running-clock");
1543 if (result === '0-1') {
1544 document.getElementById("whiteclock").textContent = "0";
1545 document.getElementById("blackclock").textContent = "1";
1546 document.getElementById("whiteclock").classList.remove("running-clock");
1547 document.getElementById("blackclock").classList.remove("running-clock");
1552 let white_clock_ms = null;
1553 let black_clock_ms = null;
1556 if (data['position'] &&
1557 data['position']['white_clock'] &&
1558 data['position']['black_clock']) {
1559 white_clock_ms = data['position']['white_clock'] * 1000;
1560 black_clock_ms = data['position']['black_clock'] * 1000;
1563 // Dynamic clock (only one, obviously).
1565 if (data['position']['white_clock_target']) {
1567 document.getElementById("whiteclock").classList.add("running-clock");
1568 document.getElementById("blackclock").classList.remove("running-clock");
1569 } else if (data['position']['black_clock_target']) {
1571 document.getElementById("whiteclock").classList.remove("running-clock");
1572 document.getElementById("blackclock").classList.add("running-clock");
1574 document.getElementById("whiteclock").classList.remove("running-clock");
1575 document.getElementById("blackclock").classList.remove("running-clock");
1579 let now = new Date().getTime() + client_clock_offset_ms;
1580 remaining_ms = data['position'][color + '_clock_target'] * 1000 - now;
1581 if (color === "white") {
1582 white_clock_ms = remaining_ms;
1584 black_clock_ms = remaining_ms;
1588 if (white_clock_ms === null || black_clock_ms === null) {
1589 document.getElementById("whiteclock").replaceChildren();
1590 document.getElementById("blackclock").replaceChildren();
1594 // If either player has twenty minutes or less left, add the second counters.
1595 // This matches what DGT clocks do.
1596 let show_seconds = (white_clock_ms < 60 * 20 * 1000 || black_clock_ms < 60 * 20 * 1000);
1599 // See when the clock will change next, and update right after that.
1602 next_update_ms = remaining_ms % 1000 + 100;
1604 next_update_ms = remaining_ms % 60000 + 100;
1606 clock_timer = setTimeout(update_clock, next_update_ms);
1609 document.getElementById("whiteclock").textContent = format_clock(white_clock_ms, show_seconds);
1610 document.getElementById("blackclock").textContent = format_clock(black_clock_ms, show_seconds);
1614 * @param {Number} remaining_ms
1615 * @param {boolean} show_seconds
1617 function format_clock(remaining_ms, show_seconds) {
1618 if (remaining_ms <= 0) {
1626 let remaining = Math.floor(remaining_ms / 1000);
1627 let seconds = remaining % 60;
1628 remaining = (remaining - seconds) / 60;
1629 let minutes = remaining % 60;
1630 remaining = (remaining - minutes) / 60;
1631 let hours = remaining;
1633 return format_2d(hours) + ":" + format_2d(minutes) + ":" + format_2d(seconds);
1635 return format_2d(hours) + ":" + format_2d(minutes);
1642 function format_2d(x) {
1651 * @param {string} move
1652 * @param {Number} move_num Move number of this move.
1653 * @param {boolean} white_to_play Whether white is to play this move.
1655 function format_move_with_number(move, move_num, white_to_play) {
1657 if (white_to_play) {
1658 ret = move_num + '. ';
1660 ret = move_num + '… ';
1667 * @param {string} move
1668 * @param {Number} halfmove_num Half-move number that is to be played,
1671 function format_halfmove_with_number(move, halfmove_num) {
1672 return format_move_with_number(
1674 Math.floor(halfmove_num / 2) + 1,
1675 halfmove_num % 2 == 0);
1679 * @param {Object} data
1680 * @param {Number} halfmove_num
1682 function format_tooltip(data, halfmove_num) {
1683 if (data['score_history'][halfmove_num + 1] ||
1684 (halfmove_num + 1) === data['position']['history'].length) {
1685 // Position is in the history, or it is the current position
1686 // (which is implicitly tacked onto the history).
1689 if ((halfmove_num + 1) === data['position']['history'].length) {
1690 move = data['position']['last_move'];
1691 short_score = format_short_score(data['score']);
1693 move = data['position']['history'][halfmove_num];
1694 short_score = format_short_score(data['score_history'][halfmove_num + 1]);
1696 if (halfmove_num === -1) {
1697 return "Start position: " + short_score;
1699 let move_with_number = format_halfmove_with_number(move, halfmove_num);
1700 return "After " + move_with_number + ": " + short_score;
1703 for (let i = halfmove_num; i --> -1; ) {
1704 if (data['score_history'][i]) {
1705 let move = data['position']['history'][i];
1707 return "[Analysis kept from start position]";
1709 return "[Analysis kept from " + format_halfmove_with_number(move, i) + "]";
1717 * @param {boolean} truncate_history
1719 function set_truncate_history(truncate_history) {
1720 truncate_display_history = truncate_history;
1721 update_refutation_lines();
1723 window['set_truncate_history'] = set_truncate_history;
1726 * @param {number} line_num
1727 * @param {number} move_num
1729 function show_line(line_num, move_num) {
1730 if (line_num == -1) {
1731 current_display_line = null;
1732 current_display_move = null;
1733 hash_refutation_lines = null;
1734 if (displayed_analysis_data) {
1735 // TODO: Support exiting to history position if we are in an
1736 // analysis line of a history position.
1737 displayed_analysis_data = null;
1742 current_display_line = {...display_lines[line_num]}; // Shallow clone.
1743 current_display_move = move_num + current_display_line.start_display_move_num;
1745 current_display_line_is_history = (line_num == 0);
1747 update_historic_analysis();
1748 update_displayed_line();
1749 update_board_highlight();
1750 update_move_highlight();
1753 window['show_line'] = show_line;
1755 function prev_move() {
1756 if (current_display_line &&
1757 current_display_move >= current_display_line.start_display_move_num) {
1758 --current_display_move;
1760 update_historic_analysis();
1761 update_displayed_line();
1762 update_move_highlight();
1764 window['prev_move'] = prev_move;
1766 function next_move() {
1767 if (current_display_line &&
1768 current_display_move < current_display_line.pv.length - 1) {
1769 ++current_display_move;
1771 update_historic_analysis();
1772 update_displayed_line();
1773 update_move_highlight();
1775 window['next_move'] = next_move;
1777 function next_game() {
1778 if (current_games === null) {
1782 // Try to find the game we are currently looking at.
1783 for (let game_num = 0; game_num < current_games.length; ++game_num) {
1784 let game = current_games[game_num];
1785 if (game['url'] === backend_url) {
1786 let next_game_num = (game_num + 1) % current_games.length;
1787 switch_backend(current_games[next_game_num]);
1792 // Couldn't find it; give up.
1795 function update_historic_analysis() {
1796 if (!current_display_line_is_history) {
1799 if (current_display_move == current_display_line.pv.length - 1) {
1800 displayed_analysis_data = null;
1804 // Fetch old analysis for this line if it exists.
1805 let hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pv, current_display_move);
1806 let filename = "/history/move" + (current_display_move + 1) + "-" +
1807 hiddenboard.fen().replace(/ /g, '_').replace(/\//g, '-') + ".json";
1809 let handle_err = () => {
1810 displayed_analysis_data = {'failed': true};
1814 current_historic_xhr = new AbortController();
1815 const signal = current_analysis_xhr.signal;
1816 fetch(filename, { signal })
1817 .then((response) => response.json().then(data => ({ok: response.ok, json: data}))) // ick
1823 displayed_analysis_data = obj.json;
1827 if (err.name === 'AbortError') {
1828 // Aborted because we are switching backends. Abandon and don't retry,
1829 // because another one is already started for us.
1838 * @param {string} fen
1840 function update_imbalance(fen) {
1841 let imbalance = {'k': 0, 'q': 0, 'r': 0, 'b': 0, 'n': 0, 'p': 0};
1842 for (const c of fen) {
1847 if (c != c.toUpperCase()) {
1849 } else if (c != c.toLowerCase()) {
1850 ++imbalance[c.toLowerCase()];
1854 let white_imbalance = document.getElementById('whiteimbalance');
1855 let black_imbalance = document.getElementById('blackimbalance');
1856 white_imbalance.textContent = '';
1857 black_imbalance.textContent = '';
1858 for (let piece in imbalance) {
1859 for (let i = 0; i < imbalance[piece]; ++i) {
1860 let i1 = document.createElement('img');
1861 i1.src = svg_pieces['w' + piece.toUpperCase()];
1862 i1.setAttribute('alt', piece.toUpperCase());
1863 i1.classList.add('imbalance-piece');
1864 white_imbalance.appendChild(i1);
1866 let i2 = document.createElement('img');
1867 i2.src = svg_pieces['b' + piece.toUpperCase()];
1868 i2.setAttribute('alt', piece.toUpperCase());
1869 i2.classList.add('imbalance-inverted-piece');
1870 white_imbalance.appendChild(i2);
1872 for (let i = 0; i < -imbalance[piece]; ++i) {
1873 let i1 = document.createElement('img');
1874 i1.src = svg_pieces['b' + piece.toUpperCase()];
1875 i1.setAttribute('alt', piece.toUpperCase());
1876 i1.classList.add('imbalance-piece');
1877 black_imbalance.appendChild(i1);
1879 let i2 = document.createElement('img');
1880 i2.src = svg_pieces['w' + piece.toUpperCase()];
1881 i2.setAttribute('alt', piece.toUpperCase());
1882 i2.classList.add('imbalance-inverted-piece');
1883 black_imbalance.appendChild(i2);
1888 /** Mark the currently selected move in red.
1889 * Also replaces the PV with the current displayed line if it's not shown
1890 * anywhere else on the screen.
1892 function update_move_highlight() {
1893 if (highlighted_move !== null) {
1894 highlighted_move.classList.remove('highlight');
1896 if (current_display_line) {
1897 let display_line_num = find_display_line_matching_num();
1898 if (display_line_num === null) {
1899 // Replace the PV with the (complete) line.
1900 document.getElementById("pvtitle").textContent = "Exploring:";
1901 current_display_line.start_display_move_num = 0;
1902 display_lines.push(current_display_line);
1903 document.getElementById("pv").append(print_pv(display_lines.length - 1, null)); // FIXME
1904 display_line_num = display_lines.length - 1;
1906 // Clear out the PV, so it's not selected by anything later.
1907 display_lines[1].pv = [];
1910 highlighted_move = document.getElementById("automove" + display_line_num + "-" + (current_display_move - current_display_line.start_display_move_num));
1911 if (highlighted_move !== null) {
1912 highlighted_move.classList.add('highlight');
1918 * See if the current displayed line is identical to any of the ones
1919 * we have on screen. (It might not be if e.g. the analysis reloaded
1920 * since we started looking.)
1924 function find_display_line_matching_num() {
1925 for (let i = 0; i < display_lines.length; ++i) {
1926 let line = display_lines[i];
1927 if (line.start_display_move_num > 0) continue;
1928 if (current_display_line.start_fen !== line.start_fen) continue;
1929 if (current_display_line.pv.length !== line.pv.length) continue;
1931 for (let j = 0; j < line.pv.length; ++j) {
1932 if (current_display_line.pv[j] !== line.pv[j]) {
1944 /** Update the board based on the currently displayed line.
1946 * TODO: This should really be called only whenever something changes,
1947 * instead of all the time.
1949 function update_displayed_line() {
1950 if (current_display_line === null) {
1951 document.getElementById("linenav").style.display = 'none';
1952 document.getElementById("linemsg").style.display = 'revert';
1953 display_fen = base_fen;
1954 set_board_position(base_fen);
1955 update_imbalance(base_fen);
1959 document.getElementById("linenav").style.display = 'revert';
1960 document.getElementById("linemsg").style.display = 'none';
1962 if (current_display_move <= 0) {
1963 document.getElementById("prevmove").textContent = "Previous";
1965 document.getElementById("prevmove").innerHTML = "<a href=\"javascript:prev_move();\">Previous</a></span>";
1967 if (current_display_move == current_display_line.pv.length - 1) {
1968 document.getElementById("nextmove").textContent = "Next";
1970 document.getElementById("nextmove").innerHTML = "<a href=\"javascript:next_move();\">Next</a></span>";
1973 let hiddenboard = chess_from(current_display_line.start_fen, current_display_line.pv, current_display_move);
1974 set_board_position(hiddenboard.fen());
1975 if (display_fen !== hiddenboard.fen() && !current_display_line_is_history) {
1976 // Fire off a hash request, since we're now off the main position
1977 // and it just changed.
1978 explore_hash(hiddenboard.fen());
1980 display_fen = hiddenboard.fen();
1981 update_imbalance(hiddenboard.fen());
1984 function set_board_position(new_fen) {
1985 board_is_animating = true;
1986 let old_fen = board.fen();
1987 board.position(new_fen);
1988 if (board.fen() === old_fen) {
1989 board_is_animating = false;
1994 * @param {boolean} param_enable_sound
1996 function set_sound(param_enable_sound) {
1997 enable_sound = param_enable_sound;
1999 document.getElementById("soundon").innerHTML = "<strong>On</strong>";
2000 document.getElementById("soundoff").innerHTML = "<a href=\"javascript:set_sound(false)\">Off</a>";
2002 // Seemingly at least Firefox prefers MP3 over Opus; tell it otherwise,
2003 // and also preload the file since the user has selected audio.
2004 let ding = document.getElementById('ding');
2005 if (ding && ding.canPlayType && ding.canPlayType('audio/ogg; codecs="opus"') === 'probably') {
2006 ding.src = 'ding.opus';
2010 document.getElementById("soundon").innerHTML = "<a href=\"javascript:set_sound(true)\">On</a>";
2011 document.getElementById("soundoff").innerHTML = "<strong>Off</strong>";
2013 if (supports_html5_storage()) {
2014 window['localStorage']['enable_sound'] = enable_sound ? 1 : 0;
2017 window['set_sound'] = set_sound;
2019 /** Send off a hash probe request to the backend.
2020 * @param {string} fen
2022 function explore_hash(fen) {
2023 // If we already have a backend response going, abort it.
2024 if (current_hash_xhr) {
2025 current_hash_xhr.abort();
2027 if (current_hash_display_timer) {
2028 clearTimeout(current_hash_display_timer);
2029 current_hash_display_timer = null;
2031 document.getElementById("refutationlines").replaceChildren();
2033 current_hash_xhr = new AbortController();
2034 const signal = current_analysis_xhr.signal;
2035 fetch(backend_hash_url + "?fen=" + fen, { signal })
2036 .then((response) => response.json())
2037 .then((data) => { show_explore_hash_results(data, fen); })
2039 // Truncate the lines, since we already cleared the display.
2040 display_lines = [ display_lines[0], display_lines[1] ];
2041 update_move_highlight();
2045 /** Process the JSON response from a hash probe request.
2046 * @param {!Object} data
2047 * @param {string} fen
2049 function show_explore_hash_results(data, fen) {
2050 if (board_is_animating) {
2051 // Updating while the animation is still going causes
2052 // the animation to jerk. This is pretty crude, but it will do.
2053 current_hash_display_timer = setTimeout(function() { show_explore_hash_results(data, fen); }, 100);
2056 current_hash_display_timer = null;
2057 hash_refutation_lines = data['lines'];
2061 // almost all of this stuff comes from the chessboard.js example page
2062 function onDragStart(source, piece, position, orientation) {
2063 let pseudogame = new Chess(display_fen);
2064 if (pseudogame.game_over() === true ||
2065 (pseudogame.turn() === 'w' && piece.search(/^b/) !== -1) ||
2066 (pseudogame.turn() === 'b' && piece.search(/^w/) !== -1)) {
2070 recommended_move = get_best_move(pseudogame, source, null, pseudogame.turn() === 'b');
2071 if (recommended_move) {
2072 let squareEl = document.querySelector('#board .square-' + recommended_move.to);
2073 squareEl.classList.add('highlight1-32417');
2078 function mousedownSquare(e) {
2079 if (!e.target || !e.target.getAttribute('data-square')) {
2083 reverse_dragging_from = null;
2084 let square = e.target.getAttribute('data-square');
2086 let pseudogame = new Chess(display_fen);
2087 if (pseudogame.game_over() === true) {
2091 // If the square is empty, or has a piece of the side not to move,
2092 // we handle it. If not, normal piece dragging will take it.
2093 let position = board.position();
2094 if (!position.hasOwnProperty(square) ||
2095 (pseudogame.turn() === 'w' && position[square].search(/^b/) !== -1) ||
2096 (pseudogame.turn() === 'b' && position[square].search(/^w/) !== -1)) {
2097 reverse_dragging_from = square;
2098 recommended_move = get_best_move(pseudogame, null, square, pseudogame.turn() === 'b');
2099 if (recommended_move) {
2100 let squareEl = document.querySelector('#board .square-' + recommended_move.from);
2101 squareEl.classList.add('highlight1-32417');
2102 squareEl = document.querySelector('#board .square-' + recommended_move.to);
2103 squareEl.classList.add('highlight1-32417');
2108 function mouseupSquare(e) {
2109 if (!e.target || !e.target.getAttribute('data-square')) {
2112 if (reverse_dragging_from === null) {
2115 let source = e.target.getAttribute('data-square');
2116 let target = reverse_dragging_from;
2117 reverse_dragging_from = null;
2118 if (onDrop(source, target) !== 'snapback') {
2119 onSnapEnd(source, target);
2121 document.getElementById("board").querySelectorAll('.square-55d63.highlight1-32417').forEach((square) => {
2122 square.classList.remove('highlight1-32417');
2126 function get_best_move(game, source, target, invert) {
2127 let moves = game.moves({ verbose: true });
2128 if (source !== null) {
2129 moves = moves.filter(function(move) { return move.from == source; });
2131 if (target !== null) {
2132 moves = moves.filter(function(move) { return move.to == target; });
2134 if (moves.length == 0) {
2137 if (moves.length == 1) {
2141 // More than one move. Use the display lines (if we have them)
2142 // to disambiguate; otherwise, we have no information.
2144 for (let i = 0; i < moves.length; ++i) {
2145 move_hash[moves[i].san] = moves[i];
2148 // See if we're already exploring some line.
2149 if (current_display_line &&
2150 current_display_move < current_display_line.pv.length - 1) {
2151 let first_move = current_display_line.pv[current_display_move + 1];
2152 if (move_hash[first_move]) {
2153 return move_hash[first_move];
2157 // History and PV take priority over the display lines.
2158 for (let i = 0; i < 2; ++i) {
2159 let line = display_lines[i];
2160 let first_move = line.pv[line.start_display_move_num];
2161 if (move_hash[first_move]) {
2162 return move_hash[first_move];
2166 let best_move = null;
2167 let best_move_score = null;
2169 for (let move in refutation_lines) {
2170 let line = refutation_lines[move];
2171 if (!line['score']) {
2174 let first_move = line['pv'][0];
2175 if (move_hash[first_move]) {
2176 let score = compute_score_sort_key(line['score'], line['depth'], invert);
2177 if (best_move_score === null || score > best_move_score) {
2178 best_move = move_hash[first_move];
2179 best_move_score = score;
2186 function onDrop(source, target) {
2187 if (source === target) {
2188 if (recommended_move === null) {
2191 // Accept the move. It will be changed in onSnapEnd.
2195 // Suggestion not asked for.
2196 recommended_move = null;
2199 // see if the move is legal
2200 let pseudogame = new Chess(display_fen);
2201 let move = pseudogame.move({
2204 promotion: 'q' // NOTE: always promote to a queen for example simplicity
2208 if (move === null) return 'snapback';
2211 function onSnapEnd(source, target) {
2212 if (source === target && recommended_move !== null) {
2213 source = recommended_move.from;
2214 target = recommended_move.to;
2216 recommended_move = null;
2217 let pseudogame = new Chess(display_fen);
2218 let move = pseudogame.move({
2221 promotion: 'q' // NOTE: always promote to a queen for example simplicity
2224 // Move ahead on the line we're on -- this includes history if we've
2226 if (current_display_line &&
2227 current_display_move < current_display_line.pv.length - 1 &&
2228 current_display_line.pv[current_display_move + 1] === move.san) {
2233 // Walk down the displayed lines until we find one that starts with
2234 // this move, then select that. Note that this gives us a good priority
2235 // order (PV, then multi-PV lines; history was already dealt with above,
2236 // as it's the only line that originates backwards).
2237 for (let i = 1; i < display_lines.length; ++i) {
2238 if (i == 1 && current_display_line) {
2239 // Do not choose PV if not on it.
2242 let line = display_lines[i];
2243 if (line.pv[line.start_display_move_num] === move.san) {
2249 // Shouldn't really be here if we have hash probes, but there's really
2250 // nothing we can do.
2251 // FIXME: Just make a new line, probably (even if we don't have hash moves).
2252 // As it is, we can actually drag (but not click) such a move in the UI,
2253 // but it has no effect on what we're probing.
2255 // End of dragging-related code.
2257 function fmt_cp(v) {
2261 return "+" + (v / 100).toFixed(2);
2264 return "-" + (v / 100).toFixed(2);
2268 function format_short_score(score) {
2272 if (score[0] === 'T' || score[0] === 't') {
2273 let ret = "TB\u00a0";
2274 if (score[2]) { // Is a bound.
2275 ret = score[2] + "\u00a0TB\u00a0";
2277 if (score[0] === 'T') {
2278 return ret + Math.ceil(score[1] / 2);
2280 return ret + "-" + Math.ceil(score[1] / 2);
2282 } else if (score[0] === 'M' || score[0] === 'm') {
2283 let sign = (score[0] === 'm') ? '-' : '';
2284 if (score[2]) { // Is a bound.
2285 return score[2] + "\u00a0M " + sign + score[1];
2287 return "M " + sign + score[1];
2289 } else if (score[0] === 'd') {
2291 } else if (score[0] === 'cp') {
2292 if (score[2]) { // Is a bound.
2293 return score[2] + "\u00a0" + fmt_cp(score[1]);
2295 return fmt_cp(score[1]);
2301 function format_long_score(score) {
2305 if (score[0] === 'T') {
2306 if (score[1] == 0) {
2307 return "Won for white (tablebase)";
2309 return "White wins in " + Math.ceil(score[1] / 2);
2311 } else if (score[0] === 't') {
2312 if (score[1] == -1) {
2313 return "Won for black (tablebase)";
2315 return "Black wins in " + Math.ceil(score[1] / 2);
2317 } else if (score[0] === 'M') {
2318 if (score[1] == 0) {
2319 return "White wins by checkmate";
2321 return "White mates in " + score[1];
2323 } else if (score[0] === 'm') {
2324 if (score[1] == 0) {
2325 return "Black wins by checkmate";
2327 return "Black mates in " + score[1];
2329 } else if (score[0] === 'd') {
2330 return "Theoretical draw";
2331 } else if (score[0] === 'cp') {
2332 return "Score: " + format_short_score(score);
2337 function compute_plot_score(score) {
2338 if (score[0] === 'M' || score[0] === 'T') {
2340 } else if (score[0] === 'm' || score[0] === 't') {
2342 } else if (score[0] === 'd') {
2344 } else if (score[0] === 'cp') {
2345 if (score[1] > 500) {
2347 } else if (score[1] < -500) {
2357 * @param score The score digest tuple.
2358 * @param {?number} depth Depth the move has been computed to, or null.
2359 * @param {boolean} invert Whether black is to play.
2362 function compute_score_sort_key(score, depth, invert) {
2367 if (score[0] === 'T') {
2368 // White reaches TB win.
2369 s = 89999 - score[1];
2370 } else if (score[0] === 't') {
2371 // Black reaches TB win.
2372 s = -(89999 - score[1]);
2373 } else if (score[0] === 'M') {
2375 s = 99999 - score[1];
2376 } else if (score[0] === 'm') {
2378 s = -(99999 - score[1]);
2379 } else if (score[0] === 'd') {
2381 } else if (score[0] === 'cp') {
2393 * @param {Object} game
2395 function switch_backend(game) {
2396 // Stop looking at historic data.
2397 current_display_line = null;
2398 current_display_move = null;
2399 displayed_analysis_data = null;
2400 if (current_historic_xhr) {
2401 current_historic_xhr.abort();
2404 // If we already have a backend response going, abort it.
2405 if (current_analysis_xhr) {
2406 current_analysis_xhr.abort();
2408 if (current_hash_xhr) {
2409 current_hash_xhr.abort();
2412 // Otherwise, we should have a timer going to start a new one.
2414 if (current_analysis_request_timer) {
2415 clearTimeout(current_analysis_request_timer);
2416 current_analysis_request_timer = null;
2418 if (current_hash_display_timer) {
2419 clearTimeout(current_hash_display_timer);
2420 current_hash_display_timer = null;
2423 // Request an immediate fetch with the new backend.
2424 backend_url = game['url'];
2425 backend_hash_url = game['hashurl'];
2426 window.location.hash = '#' + game['id'];
2427 current_analysis_data = null;
2431 window['switch_backend'] = switch_backend;
2433 window['flip'] = function() { board.flip(); redraw_arrows(); };
2434 window['set_delay_ms'] = function(ms) { delay_ms = ms; console.log('Delay is now ' + ms + ' ms.'); };
2436 // Mostly from Wikipedia's chess set as of October 2022, but some pieces are from
2437 // the 2013 version, as I like those better (and it matches the 2014 PNGs; nobody
2438 // really likes change, do they?). That is wK, bK, bQ. wQ is also slightly different,
2439 // but not enough to notice.
2440 const svg_pieces = {
2441 'wK': 'data:image/svg+xml,<?xml version=%221.0%22 encoding=%22UTF-8%22 standalone=%22no%22?>%0A<!DOCTYPE svg PUBLIC %22-//W3C//DTD SVG 1.1//EN%22 %22http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd%22>%0A<svg xmlns=%22http://www.w3.org/2000/svg%22 version=%221.1%22 width=%2245%22 height=%2245%22><g style=%22fill:none;fill-opacity:1;fill-rule:evenodd;stroke:%23000000;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1%22><path d=%22M 22.5,11.63 L 22.5,6%22 style=%22fill:none;stroke:%23000000;stroke-linejoin:miter%22/><path d=%22M 20,8 L 25,8%22 style=%22fill:none;stroke:%23000000;stroke-linejoin:miter%22/><path d=%22M 22.5,25 C 22.5,25 27,17.5 25.5,14.5 C 25.5,14.5 24.5,12 22.5,12 C 20.5,12 19.5,14.5 19.5,14.5 C 18,17.5 22.5,25 22.5,25%22 style=%22fill:%23ffffff;stroke:%23000000;stroke-linecap:butt;stroke-linejoin:miter%22/><path d=%22M 11.5,37 C 17,40.5 27,40.5 32.5,37 L 32.5,30 C 32.5,30 41.5,25.5 38.5,19.5 C 34.5,13 25,16 22.5,23.5 L 22.5,27 L 22.5,23.5 C 19,16 9.5,13 6.5,19.5 C 3.5,25.5 11.5,29.5 11.5,29.5 L 11.5,37 z %22 style=%22fill:%23ffffff;stroke:%23000000%22/><path d=%22M 11.5,30 C 17,27 27,27 32.5,30%22 style=%22fill:none;stroke:%23000000%22/><path d=%22M 11.5,33.5 C 17,30.5 27,30.5 32.5,33.5%22 style=%22fill:none;stroke:%23000000%22/><path d=%22M 11.5,37 C 17,34 27,34 32.5,37%22 style=%22fill:none;stroke:%23000000%22/></g></svg>',
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2450 'bB': 'data:image/svg+xml,<?xml version=%221.0%22 encoding=%22UTF-8%22 standalone=%22no%22?>%0A<!DOCTYPE svg PUBLIC %22-//W3C//DTD SVG 1.1//EN%22 %22http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd%22>%0A<svg xmlns=%22http://www.w3.org/2000/svg%22 version=%221.1%22 width=%2245%22 height=%2245%22><g style=%22opacity:1;fill:none;fill-rule:evenodd;fill-opacity:1;stroke:%23000000;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1%22 transform=%22translate(0,0.6)%22><g style=%22fill:%23000000;stroke:%23000000;stroke-linecap:butt%22><path d=%22M 9,36 C 12.39,35.03 19.11,36.43 22.5,34 C 25.89,36.43 32.61,35.03 36,36 C 36,36 37.65,36.54 39,38 C 38.32,38.97 37.35,38.99 36,38.5 C 32.61,37.53 25.89,38.96 22.5,37.5 C 19.11,38.96 12.39,37.53 9,38.5 C 7.65,38.99 6.68,38.97 6,38 C 7.35,36.54 9,36 9,36 z%22/><path d=%22M 15,32 C 17.5,34.5 27.5,34.5 30,32 C 30.5,30.5 30,30 30,30 C 30,27.5 27.5,26 27.5,26 C 33,24.5 33.5,14.5 22.5,10.5 C 11.5,14.5 12,24.5 17.5,26 C 17.5,26 15,27.5 15,30 C 15,30 14.5,30.5 15,32 z%22/><path d=%22M 25 8 A 2.5 2.5 0 1 1 20,8 A 2.5 2.5 0 1 1 25 8 z%22/></g><path d=%22M 17.5,26 L 27.5,26 M 15,30 L 30,30 M 22.5,15.5 L 22.5,20.5 M 20,18 L 25,18%22 style=%22fill:none;stroke:%23ffffff;stroke-linejoin:miter%22/></g></svg>',
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2452 'bP': 'data:image/svg+xml,<?xml version=%221.0%22 encoding=%22UTF-8%22 standalone=%22no%22?>%0A<!DOCTYPE svg PUBLIC %22-//W3C//DTD SVG 1.1//EN%22 %22http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd%22>%0A<svg xmlns=%22http://www.w3.org/2000/svg%22 version=%221.1%22 width=%2245%22 height=%2245%22><path d=%22m 22.5,9 c -2.21,0 -4,1.79 -4,4 0,0.89 0.29,1.71 0.78,2.38 C 17.33,16.5 16,18.59 16,21 c 0,2.03 0.94,3.84 2.41,5.03 C 15.41,27.09 11,31.58 11,39.5 H 34 C 34,31.58 29.59,27.09 26.59,26.03 28.06,24.84 29,23.03 29,21 29,18.59 27.67,16.5 25.72,15.38 26.21,14.71 26.5,13.89 26.5,13 c 0,-2.21 -1.79,-4 -4,-4 z%22 style=%22opacity:1;fill:%23000000;fill-opacity:1;fill-rule:nonzero;stroke:%23000000;stroke-width:1.5;stroke-linecap:round;stroke-linejoin:miter;stroke-miterlimit:4;stroke-dasharray:none;stroke-opacity:1%22/></svg>',
2455 function svg_piece_theme(piece) {
2456 return svg_pieces[piece];
2460 unique = get_unique();
2462 // Load settings from HTML5 local storage if available.
2463 if (supports_html5_storage() && window['localStorage']['enable_sound']) {
2464 set_sound(parseInt(window['localStorage']['enable_sound']));
2470 board = new window.ChessBoard('board', {
2471 onMoveEnd: function() { board_is_animating = false; },
2474 pieceTheme: svg_piece_theme,
2475 onDragStart: onDragStart,
2477 onSnapEnd: onSnapEnd
2479 document.getElementById("board").addEventListener('mousedown', mousedownSquare);
2480 document.getElementById("board").addEventListener('mouseup', mouseupSquare);
2483 window.addEventListener('resize', function() {
2485 update_sparkline(displayed_analysis_data || current_analysis_data);
2486 update_board_highlight();
2489 new ResizeObserver(() => update_sparkline(displayed_analysis_data || current_analysis_data)).observe(document.getElementById('scoresparkcontainer'));
2490 window.addEventListener('keyup', function(event) {
2491 if (event.which == 39) { // Left arrow.
2493 } else if (event.which == 37) { // Right arrow.
2495 } else if (event.which >= 49 && event.which <= 57) { // 1-9.
2496 let num = event.which - 49;
2497 if (current_games && current_games.length >= num) {
2498 switch_backend(current_games[num]);
2500 } else if (event.which == 78) { // N.
2504 window.addEventListener('hashchange', possibly_switch_game_from_hash, false);
2505 possibly_switch_game_from_hash();
2507 document.addEventListener('DOMContentLoaded', init);