Stop replaying the game every move; Chess.js is so slow, it eventually takes hundreds...

diff --git a/www/js/book.js b/www/js/book.js
index 36a9a26183b90c3797cd6ed982022653eb14a377..599805832b694da7779bf161091f77c49cd4ab66 100644 (file)
--- a/www/js/book.js
+++ b/www/js/book.js
@@ -1,7 +1,8 @@
 (function() {
 
 var board = null;
-var history = [];
+var game = new Chess();
+var fens = [];
 var move_override = 0;
 var includetransp = true;
 
@@ -19,40 +20,36 @@ function escape_html(string) {
        });
 }
 
-var get_game = function(skip_last_move) {
-       var moves_to_drop = 0;
-       if (skip_last_move === true) {
-               moves_to_drop = 1;
-       }
-
-       var game = new Chess();
-       for (var i = 0; i < move_override - moves_to_drop; ++i) {
-               game.move(history[i]);
+var current_display_fen = function() {
+       if (move_override == 0) {
+               return 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1';
+       } else {
+               return fens[move_override - 1];
        }
-       return game;
 }
 
 var update = function() {
        var text = "";
+       var history = game.history({ verbose: true });
        for (var i = 0; i < history.length; ++i) {
                if (i % 2 == 0) {
                        text += (i/2 + 1) + ". ";
                }
                if (i + 1 == move_override) {
-                       text += '<strong>' + history[i] + '</strong>';
+                       text += '<strong>' + history[i].san + '</strong>';
                } else {
-                       text += '<a href="javascript:set_move(' + (i + 1) + ')">' + history[i] + '</a>';
+                       text += '<a href="javascript:set_move(' + (i + 1) + ')">' + history[i].san + '</a>';
                }
                text += " ";
        }
        $('#gamehistory').html(text);
 
-       var game = get_game();
-       board.position(game.fen());
+       if (board.fen() != current_display_fen()) {
+               board.position(current_display_fen());
+       }
 
-       var all_moves = game.history({ verbose: true });
-       if (all_moves.length > 0) {
-               var last_move = all_moves.pop();
+       if (move_override > 0) {
+               var last_move = history[move_override - 1];
                var highlight_from = last_move.from;
                var highlight_to = last_move.to;
                $("#board").find('.square-55d63').removeClass('nonuglyhighlight');
@@ -64,8 +61,7 @@ var update = function() {
 }
 
 var fetch_analysis = function() {
-       var game = get_game();
-       var fen = game.fen();
+       var fen = current_display_fen();
        $.ajax({
                url: "/opening-stats.pl?fen=" + encodeURIComponent(fen) +
                        ";includetransp=" + (includetransp ? 1 : 0)
@@ -174,7 +170,7 @@ var show_lines = function(data, game) {
 
                // Win%.
                var white_win_ratio = (white + 0.5 * draw) / num;
-               var win_ratio = (game.turn() == 'w') ? white_win_ratio : 1.0 - white_win_ratio;
+               var win_ratio = (i % 2 == 0) ? white_win_ratio : 1.0 - white_win_ratio;
                line.push(win_ratio);
 
                line.push(white);        // WWin.
@@ -194,7 +190,7 @@ var show_lines = function(data, game) {
                        var win_elo = -400.0 * Math.log(1.0 / white_win_ratio - 1.0) / Math.LN10;
                        win_elo -= (move['white_avg_elo'] - move['black_avg_elo']);
                        white_win_ratio = 1.0 / (1.0 + Math.pow(10, win_elo / -400.0));
-                       win_ratio = (game.turn() == 'w') ? white_win_ratio : 1.0 - white_win_ratio;
+                       win_ratio = (i % 2 == 0) ? white_win_ratio : 1.0 - white_win_ratio;
                        line.push(win_ratio);
                } else {
                        line.push(null);
@@ -259,13 +255,23 @@ var set_includetransp = function(value) {
 window['set_includetransp'] = set_includetransp;
 
 var make_move = function(move) {
-       if (move_override < history.length && history[move_override] == move) {
+       var history = game.history({ verbose: true });
+       if (move_override < history.length && history[move_override].san == move) {
                // User effectively only moved forward in history.
                ++move_override;
        } else {
-               history.length = move_override;
-               history.push(move);
-               move_override = history.length;
+               var moves = game.history();
+               // Truncate the history if needed.
+               if (move_override < moves.length) {
+                       game = new Chess();
+                       for (var i = 0; i < move_override; ++i) {
+                               game.move(moves[i]);
+                       }
+                       fens.length = move_override;
+               }
+               game.move(move);
+               fens.push(game.fen());
+               ++move_override;
        }
        update();
 }
@@ -280,7 +286,7 @@ var prev_move = function() {
 window['prev_move'] = prev_move;
 
 var next_move = function() {
-       if (move_override < history.length) {
+       if (move_override < game.history().length) {
                ++move_override;
                update();
        }
@@ -295,18 +301,18 @@ window['set_move'] = set_move;
 
 // almost all of this stuff comes from the chessboard.js example page
 var onDragStart = function(source, piece, position, orientation) {
-       var game = get_game();
-       if (game.game_over() === true ||
-           (game.turn() === 'w' && piece.search(/^b/) !== -1) ||
-           (game.turn() === 'b' && piece.search(/^w/) !== -1)) {
+       var pseudogame = new Chess(current_display_fen());
+       if (pseudogame.game_over() === true ||
+           (pseudogame.turn() === 'w' && piece.search(/^b/) !== -1) ||
+           (pseudogame.turn() === 'b' && piece.search(/^w/) !== -1)) {
                return false;
        }
 }
 
 var onDrop = function(source, target) {
        // see if the move is legal
-       var game = get_game();
-       var move = game.move({
+       var pseudogame = new Chess(current_display_fen());
+       var move = pseudogame.move({
                from: source,
                to: target,
                promotion: 'q' // NOTE: always promote to a queen for example simplicity
@@ -314,22 +320,18 @@ var onDrop = function(source, target) {
 
        // illegal move
        if (move === null) return 'snapback';
+}
 
-       var new_history = game.history({ verbose: true });
-       history = [];
-       for (var i = 0; i < new_history.length; ++i) {
-               history.push(new_history[i].san);
-       }
-       move_override = history.length;
-};
+var onSnapEnd = function(source, target) {
+       var pseudogame = new Chess(current_display_fen());
+       var move = pseudogame.move({
+               from: source,
+               to: target,
+               promotion: 'q' // NOTE: always promote to a queen for example simplicity
+       });
 
-// update the board position after the piece snap 
-// for castling, en passant, pawn promotion
-var onSnapEnd = function() {
-       var game = get_game();
-       board.position(game.fen());
-       update();
-};
+       make_move(pseudogame.history({ verbose: true }).pop().san);
+}
 
 var init = function() {
        // Create board.