chess.js - npm Package Compare versions

Comparing version 0.12.1 to 0.13.0

chess.js

 /*
- * Copyright (c) 2021, Jeff Hlywa ([e-mail])
+ * Copyright (c) 2022, Jeff Hlywa ([e-mail])
  * All rights reserved.
@@ -28,127 +28,292 @@ *
 
-var Chess = function (fen) {
-  var BLACK = 'b'
-  var WHITE = 'w'
+const SYMBOLS = 'pnbrqkPNBRQK'
 
-  var EMPTY = -1
+const DEFAULT_POSITION =
+  'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'
 
-  var PAWN = 'p'
-  var KNIGHT = 'n'
-  var BISHOP = 'b'
-  var ROOK = 'r'
-  var QUEEN = 'q'
-  var KING = 'k'
+const TERMINATION_MARKERS = ['1-0', '0-1', '1/2-1/2', '*']
 
-  var SYMBOLS = 'pnbrqkPNBRQK'
+const PAWN_OFFSETS = {
+  b: [16, 32, 17, 15],
+  w: [-16, -32, -17, -15],
+}
 
-  var DEFAULT_POSITION =
-    'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'
+const PIECE_OFFSETS = {
+  n: [-18, -33, -31, -14, 18, 33, 31, 14],
+  b: [-17, -15, 17, 15],
+  r: [-16, 1, 16, -1],
+  q: [-17, -16, -15, 1, 17, 16, 15, -1],
+  k: [-17, -16, -15, 1, 17, 16, 15, -1],
+}
 
-  var TERMINATION_MARKERS = ['1-0', '0-1', '1/2-1/2', '*']
+// prettier-ignore
+const ATTACKS = [
+  20, 0, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0, 0,20, 0,
+   0,20, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0,20, 0, 0,
+   0, 0,20, 0, 0, 0, 0, 24,  0, 0, 0, 0,20, 0, 0, 0,
+   0, 0, 0,20, 0, 0, 0, 24,  0, 0, 0,20, 0, 0, 0, 0,
+   0, 0, 0, 0,20, 0, 0, 24,  0, 0,20, 0, 0, 0, 0, 0,
+   0, 0, 0, 0, 0,20, 2, 24,  2,20, 0, 0, 0, 0, 0, 0,
+   0, 0, 0, 0, 0, 2,53, 56, 53, 2, 0, 0, 0, 0, 0, 0,
+  24,24,24,24,24,24,56,  0, 56,24,24,24,24,24,24, 0,
+   0, 0, 0, 0, 0, 2,53, 56, 53, 2, 0, 0, 0, 0, 0, 0,
+   0, 0, 0, 0, 0,20, 2, 24,  2,20, 0, 0, 0, 0, 0, 0,
+   0, 0, 0, 0,20, 0, 0, 24,  0, 0,20, 0, 0, 0, 0, 0,
+   0, 0, 0,20, 0, 0, 0, 24,  0, 0, 0,20, 0, 0, 0, 0,
+   0, 0,20, 0, 0, 0, 0, 24,  0, 0, 0, 0,20, 0, 0, 0,
+   0,20, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0,20, 0, 0,
+  20, 0, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0, 0,20
+];
 
-  var PAWN_OFFSETS = {
-    b: [16, 32, 17, 15],
-    w: [-16, -32, -17, -15],
+// prettier-ignore
+const RAYS = [
+   17,  0,  0,  0,  0,  0,  0, 16,  0,  0,  0,  0,  0,  0, 15, 0,
+    0, 17,  0,  0,  0,  0,  0, 16,  0,  0,  0,  0,  0, 15,  0, 0,
+    0,  0, 17,  0,  0,  0,  0, 16,  0,  0,  0,  0, 15,  0,  0, 0,
+    0,  0,  0, 17,  0,  0,  0, 16,  0,  0,  0, 15,  0,  0,  0, 0,
+    0,  0,  0,  0, 17,  0,  0, 16,  0,  0, 15,  0,  0,  0,  0, 0,
+    0,  0,  0,  0,  0, 17,  0, 16,  0, 15,  0,  0,  0,  0,  0, 0,
+    0,  0,  0,  0,  0,  0, 17, 16, 15,  0,  0,  0,  0,  0,  0, 0,
+    1,  1,  1,  1,  1,  1,  1,  0, -1, -1,  -1,-1, -1, -1, -1, 0,
+    0,  0,  0,  0,  0,  0,-15,-16,-17,  0,  0,  0,  0,  0,  0, 0,
+    0,  0,  0,  0,  0,-15,  0,-16,  0,-17,  0,  0,  0,  0,  0, 0,
+    0,  0,  0,  0,-15,  0,  0,-16,  0,  0,-17,  0,  0,  0,  0, 0,
+    0,  0,  0,-15,  0,  0,  0,-16,  0,  0,  0,-17,  0,  0,  0, 0,
+    0,  0,-15,  0,  0,  0,  0,-16,  0,  0,  0,  0,-17,  0,  0, 0,
+    0,-15,  0,  0,  0,  0,  0,-16,  0,  0,  0,  0,  0,-17,  0, 0,
+  -15,  0,  0,  0,  0,  0,  0,-16,  0,  0,  0,  0,  0,  0,-17
+];
+
+const SHIFTS = { p: 0, n: 1, b: 2, r: 3, q: 4, k: 5 }
+
+const BITS = {
+  NORMAL: 1,
+  CAPTURE: 2,
+  BIG_PAWN: 4,
+  EP_CAPTURE: 8,
+  PROMOTION: 16,
+  KSIDE_CASTLE: 32,
+  QSIDE_CASTLE: 64,
+}
+
+const RANK_1 = 7
+const RANK_2 = 6
+const RANK_3 = 5
+const RANK_4 = 4
+const RANK_5 = 3
+const RANK_6 = 2
+const RANK_7 = 1
+const RANK_8 = 0
+
+// prettier-ignore
+const SQUARE_MAP = {
+  a8:   0, b8:   1, c8:   2, d8:   3, e8:   4, f8:   5, g8:   6, h8:   7,
+  a7:  16, b7:  17, c7:  18, d7:  19, e7:  20, f7:  21, g7:  22, h7:  23,
+  a6:  32, b6:  33, c6:  34, d6:  35, e6:  36, f6:  37, g6:  38, h6:  39,
+  a5:  48, b5:  49, c5:  50, d5:  51, e5:  52, f5:  53, g5:  54, h5:  55,
+  a4:  64, b4:  65, c4:  66, d4:  67, e4:  68, f4:  69, g4:  70, h4:  71,
+  a3:  80, b3:  81, c3:  82, d3:  83, e3:  84, f3:  85, g3:  86, h3:  87,
+  a2:  96, b2:  97, c2:  98, d2:  99, e2: 100, f2: 101, g2: 102, h2: 103,
+  a1: 112, b1: 113, c1: 114, d1: 115, e1: 116, f1: 117, g1: 118, h1: 119
+};
+
+const ROOKS = {
+  w: [
+    { square: SQUARE_MAP.a1, flag: BITS.QSIDE_CASTLE },
+    { square: SQUARE_MAP.h1, flag: BITS.KSIDE_CASTLE },
+  ],
+  b: [
+    { square: SQUARE_MAP.a8, flag: BITS.QSIDE_CASTLE },
+    { square: SQUARE_MAP.h8, flag: BITS.KSIDE_CASTLE },
+  ],
+}
+
+/* this function is used to uniquely identify ambiguous moves */
+function get_disambiguator(move, moves) {
+  var from = move.from
+  var to = move.to
+  var piece = move.piece
+
+  var ambiguities = 0
+  var same_rank = 0
+  var same_file = 0
+
+  for (var i = 0, len = moves.length; i < len; i++) {
+    var ambig_from = moves[i].from
+    var ambig_to = moves[i].to
+    var ambig_piece = moves[i].piece
+
+    /* if a move of the same piece type ends on the same to square, we'll
+     * need to add a disambiguator to the algebraic notation
+     */
+    if (piece === ambig_piece && from !== ambig_from && to === ambig_to) {
+      ambiguities++
+
+      if (rank(from) === rank(ambig_from)) {
+        same_rank++
+      }
+
+      if (file(from) === file(ambig_from)) {
+        same_file++
+      }
+    }
   }
 
-  var PIECE_OFFSETS = {
-    n: [-18, -33, -31, -14, 18, 33, 31, 14],
-    b: [-17, -15, 17, 15],
-    r: [-16, 1, 16, -1],
-    q: [-17, -16, -15, 1, 17, 16, 15, -1],
-    k: [-17, -16, -15, 1, 17, 16, 15, -1],
+  if (ambiguities > 0) {
+    /* if there exists a similar moving piece on the same rank and file as
+     * the move in question, use the square as the disambiguator
+     */
+    if (same_rank > 0 && same_file > 0) {
+      return algebraic(from)
+    } else if (same_file > 0) {
+      /* if the moving piece rests on the same file, use the rank symbol as the
+       * disambiguator
+       */
+      return algebraic(from).charAt(1)
+    } else {
+      /* else use the file symbol */
+      return algebraic(from).charAt(0)
+    }
   }
 
-  // prettier-ignore
-  var ATTACKS = [
-    20, 0, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0, 0,20, 0,
-     0,20, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0,20, 0, 0,
-     0, 0,20, 0, 0, 0, 0, 24,  0, 0, 0, 0,20, 0, 0, 0,
-     0, 0, 0,20, 0, 0, 0, 24,  0, 0, 0,20, 0, 0, 0, 0,
-     0, 0, 0, 0,20, 0, 0, 24,  0, 0,20, 0, 0, 0, 0, 0,
-     0, 0, 0, 0, 0,20, 2, 24,  2,20, 0, 0, 0, 0, 0, 0,
-     0, 0, 0, 0, 0, 2,53, 56, 53, 2, 0, 0, 0, 0, 0, 0,
-    24,24,24,24,24,24,56,  0, 56,24,24,24,24,24,24, 0,
-     0, 0, 0, 0, 0, 2,53, 56, 53, 2, 0, 0, 0, 0, 0, 0,
-     0, 0, 0, 0, 0,20, 2, 24,  2,20, 0, 0, 0, 0, 0, 0,
-     0, 0, 0, 0,20, 0, 0, 24,  0, 0,20, 0, 0, 0, 0, 0,
-     0, 0, 0,20, 0, 0, 0, 24,  0, 0, 0,20, 0, 0, 0, 0,
-     0, 0,20, 0, 0, 0, 0, 24,  0, 0, 0, 0,20, 0, 0, 0,
-     0,20, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0,20, 0, 0,
-    20, 0, 0, 0, 0, 0, 0, 24,  0, 0, 0, 0, 0, 0,20
-  ];
+  return ''
+}
 
-  // prettier-ignore
-  var RAYS = [
-     17,  0,  0,  0,  0,  0,  0, 16,  0,  0,  0,  0,  0,  0, 15, 0,
-      0, 17,  0,  0,  0,  0,  0, 16,  0,  0,  0,  0,  0, 15,  0, 0,
-      0,  0, 17,  0,  0,  0,  0, 16,  0,  0,  0,  0, 15,  0,  0, 0,
-      0,  0,  0, 17,  0,  0,  0, 16,  0,  0,  0, 15,  0,  0,  0, 0,
-      0,  0,  0,  0, 17,  0,  0, 16,  0,  0, 15,  0,  0,  0,  0, 0,
-      0,  0,  0,  0,  0, 17,  0, 16,  0, 15,  0,  0,  0,  0,  0, 0,
-      0,  0,  0,  0,  0,  0, 17, 16, 15,  0,  0,  0,  0,  0,  0, 0,
-      1,  1,  1,  1,  1,  1,  1,  0, -1, -1,  -1,-1, -1, -1, -1, 0,
-      0,  0,  0,  0,  0,  0,-15,-16,-17,  0,  0,  0,  0,  0,  0, 0,
-      0,  0,  0,  0,  0,-15,  0,-16,  0,-17,  0,  0,  0,  0,  0, 0,
-      0,  0,  0,  0,-15,  0,  0,-16,  0,  0,-17,  0,  0,  0,  0, 0,
-      0,  0,  0,-15,  0,  0,  0,-16,  0,  0,  0,-17,  0,  0,  0, 0,
-      0,  0,-15,  0,  0,  0,  0,-16,  0,  0,  0,  0,-17,  0,  0, 0,
-      0,-15,  0,  0,  0,  0,  0,-16,  0,  0,  0,  0,  0,-17,  0, 0,
-    -15,  0,  0,  0,  0,  0,  0,-16,  0,  0,  0,  0,  0,  0,-17
-  ];
+function infer_piece_type(san) {
+  var piece_type = san.charAt(0)
+  if (piece_type >= 'a' && piece_type <= 'h') {
+    var matches = san.match(/[a-h]\d.*[a-h]\d/)
+    if (matches) {
+      return undefined
+    }
+    return PAWN
+  }
+  piece_type = piece_type.toLowerCase()
+  if (piece_type === 'o') {
+    return KING
+  }
+  return piece_type
+}
+function ascii() {
+  var s = '   +------------------------+\n'
+  for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
+    /* display the rank */
+    if (file(i) === 0) {
+      s += ' ' + '87654321'[rank(i)] + ' |'
+    }
 
-  var SHIFTS = { p: 0, n: 1, b: 2, r: 3, q: 4, k: 5 }
+    /* empty piece */
+    if (board[i] == null) {
+      s += ' . '
+    } else {
+      var piece = board[i].type
+      var color = board[i].color
+      var symbol = color === WHITE ? piece.toUpperCase() : piece.toLowerCase()
+      s += ' ' + symbol + ' '
+    }
 
-  var FLAGS = {
-    NORMAL: 'n',
-    CAPTURE: 'c',
-    BIG_PAWN: 'b',
-    EP_CAPTURE: 'e',
-    PROMOTION: 'p',
-    KSIDE_CASTLE: 'k',
-    QSIDE_CASTLE: 'q',
+    if ((i + 1) & 0x88) {
+      s += '|\n'
+      i += 8
+    }
   }
+  s += '   +------------------------+\n'
+  s += '     a  b  c  d  e  f  g  h\n'
 
-  var BITS = {
-    NORMAL: 1,
-    CAPTURE: 2,
-    BIG_PAWN: 4,
-    EP_CAPTURE: 8,
-    PROMOTION: 16,
-    KSIDE_CASTLE: 32,
-    QSIDE_CASTLE: 64,
+  return s
+}
+
+// parses all of the decorators out of a SAN string
+function stripped_san(move) {
+  return move.replace(/=/, '').replace(/[+#]?[?!]*$/, '')
+}
+
+/*****************************************************************************
+ * UTILITY FUNCTIONS
+ ****************************************************************************/
+function rank(i) {
+  return i >> 4
+}
+
+function file(i) {
+  return i & 15
+}
+
+function algebraic(i) {
+  var f = file(i),
+    r = rank(i)
+  return 'abcdefgh'.substring(f, f + 1) + '87654321'.substring(r, r + 1)
+}
+
+function swap_color(c) {
+  return c === WHITE ? BLACK : WHITE
+}
+
+function is_digit(c) {
+  return '0123456789'.indexOf(c) !== -1
+}
+
+function clone(obj) {
+  var dupe = obj instanceof Array ? [] : {}
+
+  for (var property in obj) {
+    if (typeof property === 'object') {
+      dupe[property] = clone(obj[property])
+    } else {
+      dupe[property] = obj[property]
+    }
   }
 
-  var RANK_1 = 7
-  var RANK_2 = 6
-  var RANK_3 = 5
-  var RANK_4 = 4
-  var RANK_5 = 3
-  var RANK_6 = 2
-  var RANK_7 = 1
-  var RANK_8 = 0
+  return dupe
+}
 
-  // prettier-ignore
-  var SQUARES = {
-    a8:   0, b8:   1, c8:   2, d8:   3, e8:   4, f8:   5, g8:   6, h8:   7,
-    a7:  16, b7:  17, c7:  18, d7:  19, e7:  20, f7:  21, g7:  22, h7:  23,
-    a6:  32, b6:  33, c6:  34, d6:  35, e6:  36, f6:  37, g6:  38, h6:  39,
-    a5:  48, b5:  49, c5:  50, d5:  51, e5:  52, f5:  53, g5:  54, h5:  55,
-    a4:  64, b4:  65, c4:  66, d4:  67, e4:  68, f4:  69, g4:  70, h4:  71,
-    a3:  80, b3:  81, c3:  82, d3:  83, e3:  84, f3:  85, g3:  86, h3:  87,
-    a2:  96, b2:  97, c2:  98, d2:  99, e2: 100, f2: 101, g2: 102, h2: 103,
-    a1: 112, b1: 113, c1: 114, d1: 115, e1: 116, f1: 117, g1: 118, h1: 119
-  };
+function trim(str) {
+  return str.replace(/^\s+|\s+$/g, '')
+}
 
-  var ROOKS = {
-    w: [
-      { square: SQUARES.a1, flag: BITS.QSIDE_CASTLE },
-      { square: SQUARES.h1, flag: BITS.KSIDE_CASTLE },
-    ],
-    b: [
-      { square: SQUARES.a8, flag: BITS.QSIDE_CASTLE },
-      { square: SQUARES.h8, flag: BITS.KSIDE_CASTLE },
-    ],
+/***************************************************************************
+ * PUBLIC CONSTANTS
+ **************************************************************************/
+
+export const BLACK = 'b'
+export const WHITE = 'w'
+
+export const EMPTY = -1
+
+export const PAWN = 'p'
+export const KNIGHT = 'n'
+export const BISHOP = 'b'
+export const ROOK = 'r'
+export const QUEEN = 'q'
+export const KING = 'k'
+
+export const SQUARES = (function () {
+  /* from the ECMA-262 spec (section 12.6.4):
+   * "The mechanics of enumerating the properties ... is
+   * implementation dependent"
+   * so: for (var sq in SQUARES) { keys.push(sq); } might not be
+   * ordered correctly
+   */
+  var keys = []
+  for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
+    if (i & 0x88) {
+      i += 7
+      continue
+    }
+    keys.push(algebraic(i))
   }
+  return keys
+})()
 
+export const FLAGS = {
+  NORMAL: 'n',
+  CAPTURE: 'c',
+  BIG_PAWN: 'b',
+  EP_CAPTURE: 'e',
+  PROMOTION: 'p',
+  KSIDE_CASTLE: 'k',
+  QSIDE_CASTLE: 'q',
+}
+
+export const Chess = function (fen) {
   var board = new Array(128)
@@ -259,3 +424,3 @@ var kings = { w: EMPTY, b: EMPTY }
 
-    ep_square = tokens[3] === '-' ? EMPTY : SQUARES[tokens[3]]
+    ep_square = tokens[3] === '-' ? EMPTY : SQUARE_MAP[tokens[3]]
     half_moves = parseInt(tokens[4], 10)
@@ -368,3 +533,3 @@ move_number = parseInt(tokens[5], 10)
 
-    for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
+    for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
       if (board[i] == null) {
@@ -388,3 +553,3 @@ empty++
 
-        if (i !== SQUARES.h1) {
+        if (i !== SQUARE_MAP.h1) {
           fen += '/'
@@ -447,3 +612,3 @@ }
   function get(square) {
-    var piece = board[SQUARES[square]]
+    var piece = board[SQUARE_MAP[square]]
     return piece ? { type: piece.type, color: piece.color } : null
@@ -464,7 +629,7 @@ }
     /* check for valid square */
-    if (!(square in SQUARES)) {
+    if (!(square in SQUARE_MAP)) {
       return false
     }
 
-    var sq = SQUARES[square]
+    var sq = SQUARE_MAP[square]
 
@@ -491,3 +656,3 @@ /* don't let the user place more than one king */
     var piece = get(square)
-    board[SQUARES[square]] = null
+    board[SQUARE_MAP[square]] = null
     if (piece && piece.type === KING) {
@@ -545,4 +710,4 @@ kings[piece.color] = EMPTY
 
-    var first_sq = SQUARES.a8
-    var last_sq = SQUARES.h1
+    var first_sq = SQUARE_MAP.a8
+    var last_sq = SQUARE_MAP.h1
     var single_square = false
@@ -565,4 +730,4 @@
     if (typeof options !== 'undefined' && 'square' in options) {
-      if (options.square in SQUARES) {
-        first_sq = last_sq = SQUARES[options.square]
+      if (options.square in SQUARE_MAP) {
+        first_sq = last_sq = SQUARE_MAP[options.square]
         single_square = true
@@ -744,9 +909,5 @@ } else {
   }
-  // parses all of the decorators out of a SAN string
-  function stripped_san(move) {
-    return move.replace(/=/, '').replace(/[+#]?[?!]*$/, '')
-  }
 
   function attacked(color, square) {
-    for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
+    for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
       /* did we run off the end of the board */
@@ -819,3 +980,3 @@ if (i & 0x88) {
 
-    for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
+    for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
       sq_color = (sq_color + 1) % 2
@@ -1054,97 +1215,2 @@ if (i & 0x88) {
 
-  /* this function is used to uniquely identify ambiguous moves */
-  function get_disambiguator(move, moves) {
-    var from = move.from
-    var to = move.to
-    var piece = move.piece
-
-    var ambiguities = 0
-    var same_rank = 0
-    var same_file = 0
-
-    for (var i = 0, len = moves.length; i < len; i++) {
-      var ambig_from = moves[i].from
-      var ambig_to = moves[i].to
-      var ambig_piece = moves[i].piece
-
-      /* if a move of the same piece type ends on the same to square, we'll
-       * need to add a disambiguator to the algebraic notation
-       */
-      if (piece === ambig_piece && from !== ambig_from && to === ambig_to) {
-        ambiguities++
-
-        if (rank(from) === rank(ambig_from)) {
-          same_rank++
-        }
-
-        if (file(from) === file(ambig_from)) {
-          same_file++
-        }
-      }
-    }
-
-    if (ambiguities > 0) {
-      /* if there exists a similar moving piece on the same rank and file as
-       * the move in question, use the square as the disambiguator
-       */
-      if (same_rank > 0 && same_file > 0) {
-        return algebraic(from)
-      } else if (same_file > 0) {
-        /* if the moving piece rests on the same file, use the rank symbol as the
-         * disambiguator
-         */
-        return algebraic(from).charAt(1)
-      } else {
-        /* else use the file symbol */
-        return algebraic(from).charAt(0)
-      }
-    }
-
-    return ''
-  }
-
-  function infer_piece_type(san) {
-    var piece_type = san.charAt(0)
-    if (piece_type >= 'a' && piece_type <= 'h') {
-      var matches = san.match(/[a-h]\d.*[a-h]\d/)
-      if (matches) {
-        return undefined
-      }
-      return PAWN
-    }
-    piece_type = piece_type.toLowerCase()
-    if (piece_type === 'o') {
-      return KING
-    }
-    return piece_type
-  }
-  function ascii() {
-    var s = '   +------------------------+\n'
-    for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
-      /* display the rank */
-      if (file(i) === 0) {
-        s += ' ' + '87654321'[rank(i)] + ' |'
-      }
-
-      /* empty piece */
-      if (board[i] == null) {
-        s += ' . '
-      } else {
-        var piece = board[i].type
-        var color = board[i].color
-        var symbol = color === WHITE ? piece.toUpperCase() : piece.toLowerCase()
-        s += ' ' + symbol + ' '
-      }
-
-      if ((i + 1) & 0x88) {
-        s += '|\n'
-        i += 8
-      }
-    }
-    s += '   +------------------------+\n'
-    s += '     a  b  c  d  e  f  g  h\n'
-
-    return s
-  }
-
   // convert a move from Standard Algebraic Notation (SAN) to 0x88 coordinates
@@ -1225,4 +1291,4 @@ function move_from_san(move, sloppy) {
             (!piece || piece.toLowerCase() == moves[i].piece) &&
-            SQUARES[from] == moves[i].from &&
-            SQUARES[to] == moves[i].to &&
+            SQUARE_MAP[from] == moves[i].from &&
+            SQUARE_MAP[to] == moves[i].to &&
             (!promotion || promotion.toLowerCase() == moves[i].promotion)
@@ -1237,3 +1303,3 @@ ) {
               (!piece || piece.toLowerCase() == moves[i].piece) &&
-              SQUARES[to] == moves[i].to &&
+              SQUARE_MAP[to] == moves[i].to &&
               (from == square[0] || from == square[1]) &&
@@ -1252,27 +1318,2 @@ (!promotion || promotion.toLowerCase() == moves[i].promotion)
 
-  /*****************************************************************************
-   * UTILITY FUNCTIONS
-   ****************************************************************************/
-  function rank(i) {
-    return i >> 4
-  }
-
-  function file(i) {
-    return i & 15
-  }
-
-  function algebraic(i) {
-    var f = file(i),
-      r = rank(i)
-    return 'abcdefgh'.substring(f, f + 1) + '87654321'.substring(r, r + 1)
-  }
-
-  function swap_color(c) {
-    return c === WHITE ? BLACK : WHITE
-  }
-
-  function is_digit(c) {
-    return '0123456789'.indexOf(c) !== -1
-  }
-
   /* pretty = external move object */
@@ -1297,20 +1338,2 @@ function make_pretty(ugly_move) {
 
-  function clone(obj) {
-    var dupe = obj instanceof Array ? [] : {}
-
-    for (var property in obj) {
-      if (typeof property === 'object') {
-        dupe[property] = clone(obj[property])
-      } else {
-        dupe[property] = obj[property]
-      }
-    }
-
-    return dupe
-  }
-
-  function trim(str) {
-    return str.replace(/^\s+|\s+$/g, '')
-  }
-
   /*****************************************************************************
@@ -1342,32 +1365,2 @@ * DEBUGGING UTILITIES
     /***************************************************************************
-     * PUBLIC CONSTANTS (is there a better way to do this?)
-     **************************************************************************/
-    WHITE: WHITE,
-    BLACK: BLACK,
-    PAWN: PAWN,
-    KNIGHT: KNIGHT,
-    BISHOP: BISHOP,
-    ROOK: ROOK,
-    QUEEN: QUEEN,
-    KING: KING,
-    SQUARES: (function () {
-      /* from the ECMA-262 spec (section 12.6.4):
-       * "The mechanics of enumerating the properties ... is
-       * implementation dependent"
-       * so: for (var sq in SQUARES) { keys.push(sq); } might not be
-       * ordered correctly
-       */
-      var keys = []
-      for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
-        if (i & 0x88) {
-          i += 7
-          continue
-        }
-        keys.push(algebraic(i))
-      }
-      return keys
-    })(),
-    FLAGS: FLAGS,
-
-    /***************************************************************************
      * PUBLIC API
@@ -1464,7 +1457,7 @@ **************************************************************************/
 
-      for (var i = SQUARES.a8; i <= SQUARES.h1; i++) {
+      for (var i = SQUARE_MAP.a8; i <= SQUARE_MAP.h1; i++) {
         if (board[i] == null) {
           row.push(null)
         } else {
-          row.push({ type: board[i].type, color: board[i].color })
+          row.push({ square: algebraic(i), type: board[i].type, color: board[i].color })
         }
@@ -1916,4 +1909,4 @@ if ((i + 1) & 0x88) {
     square_color: function (square) {
-      if (square in SQUARES) {
-        var sq_0x88 = SQUARES[square]
+      if (square in SQUARE_MAP) {
+        var sq_0x88 = SQUARE_MAP[square]
         return (rank(sq_0x88) + file(sq_0x88)) % 2 === 0 ? 'light' : 'dark'
@@ -1981,10 +1974,1 @@ }
 }
-
-/* export Chess object if using node or any other CommonJS compatible
- * environment */
-if (typeof exports !== 'undefined') exports.Chess = Chess
-/* export Chess object for any RequireJS compatible environment */
-if (typeof define !== 'undefined')
-  define(function () {
-    return Chess
-  })

package.json

 {
   "name": "chess.js",
-  "version": "0.12.1",
+  "version": "0.13.0",
   "license": "BSD-2-Clause",
+  "type": "module",
   "main": "chess.js",
@@ -15,9 +16,9 @@ "homepage": "https://github.com/jhlywa/chess.js",
   "devDependencies": {
-    "jest": "^27.0.1",
-    "prettier": "^2.5.1"
+    "jest": "^27.5.1",
+    "prettier": "^2.6.0"
   },
   "scripts": {
-    "test": "jest",
-    "format": "prettier --write chess.js"
+    "test": "node --experimental-vm-modules node_modules/jest/bin/jest.js",
+    "format": "prettier --write **/*.{js,json}"
   }
 }

README.md

 # chess.js
 
-[![Build Status](https://travis-ci.org/jhlywa/chess.js.svg?branch=master)](https://travis-ci.org/jhlywa/chess.js)
+![GitHub Workflow Status](https://img.shields.io/github/workflow/status/jhlywa/chess.js/Node.js%20CI)
+![npm](https://img.shields.io/npm/v/chess.js?color=blue)
+![npm](https://img.shields.io/npm/dm/chess.js)
 
@@ -28,3 +30,4 @@ chess.js is a Javascript chess library that is used for chess move
 ```js
-const { Chess } = require('./chess.js')
+import { Chess } from 'chess.js';
+
 const chess = new Chess()
@@ -100,10 +103,10 @@
 chess.board()
-// -> [[{type: 'r', color: 'b'},
-        {type: 'n', color: 'b'},
-        {type: 'b', color: 'b'},
-        {type: 'q', color: 'b'},
-        {type: 'k', color: 'b'},
-        {type: 'b', color: 'b'},
-        {type: 'n', color: 'b'},
-        {type: 'r', color: 'b'}],
+// -> [[{square: 'a8', type: 'r', color: 'b'},
+        {square: 'b8', type: 'n', color: 'b'},
+        {square: 'c8', type: 'b', color: 'b'},
+        {square: 'd8', type: 'q', color: 'b'},
+        {square: 'e8', type: 'k', color: 'b'},
+        {square: 'f8', type: 'b', color: 'b'},
+        {square: 'g8', type: 'n', color: 'b'},
+        {square: 'h8', type: 'r', color: 'b'}],
         [...],
@@ -114,10 +117,10 @@ [...],
         [...],
-        [{type: 'r', color: 'w'},
-         {type: 'n', color: 'w'},
-         {type: 'b', color: 'w'},
-         {type: 'q', color: 'w'},
-         {type: 'k', color: 'w'},
-         {type: 'b', color: 'w'},
-         {type: 'n', color: 'w'},
-         {type: 'r', color: 'w'}]]
+        [{square: 'a1', type: 'r', color: 'w'},
+         {square: 'b1', type: 'n', color: 'w'},
+         {square: 'c1', type: 'b', color: 'w'},
+         {square: 'd1', type: 'q', color: 'w'},
+         {square: 'e1', type: 'k', color: 'w'},
+         {square: 'f1', type: 'b', color: 'w'},
+         {square: 'g1', type: 'n', color: 'w'},
+         {square: 'h1', type: 'r', color: 'w'}]]
 ```
@@ -124,0 +127,0 @@

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Improved metrics

Total package byte prevSize

161289

increased by5.85%

Lines of code

4509

increased by38.36%

Number of lines in readme file

746

increased by0.4%

Is type module

Yes

Worsened metrics

Number of package files

8

decreased by-11.11%

No dependency changes