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An algebraic notation driven chess engine that can validate board position and produce a list of viable moves (notated).
node-chess
- the algebraic chess enginenode-chess
is an algebraic notation driven chess engine that can validate board position and produce a list of viable moves (notated).
npm install chess
import chess from 'chess';
// create a game client
const gameClient = chess.create();
let move, status;
// capture events
gameClient.on('check', (attack) => {
// get more details about the attack on the King
console.log(attack);
});
// look at the status and valid moves
status = gameClient.getStatus();
// make a move
move = gameClient.move('a4');
// look at the status again after the move to see
// the opposing side's available moves
status = gameClient.getStatus();
To ensure the notation returned is safe for PGN, you must supply PGN as an option in the call to create
:
import chess from 'chess';
// create a game client
const gameClient = chess.create({ PGN : true });
let move, status;
// look at the status and valid moves
status = gameClient.getStatus();
// make a move
move = gameClient.move('a4');
// look at the status again after the move to see
// the opposing side's available moves
status = gameClient.getStatus();
The game client (both algebraic, simple) emit a number of events when scenarios occur on the board over the course of a match.
import chess from 'chess';
// create a game client
const gameClient = chess.create({ PGN : true });
// when a capture occurs
gameClient.on('capture', (move) => {
console.log('A piece has been captured!');
console.log(move);
});
// when a castle occurs
gameClient.on('castle', (move) => {
console.log('A castle has occured!');
console.log(move);
});
// when a King is placed in check
gameClient.on('check', (attack) => {
console.log('The King is under attack!');
console.log(attack);
});
// when King is placed in checkmate
gameClient.on('checkmate', (attack) => {
console.log('The game has ended due to checkmate!');
console.log(attack);
});
// when en Passant occurs
gameClient.on('enPassant', (move) => {
console.log('An en Passant has occured!');
console.log(move);
});
// when a move occurs on the board
gameClient.on('move', (move) => {
console.log('A piece was moved!');
console.log(move);
});
// when a Pawn promotion occurs
gameClient.on('promote', (square) => {
console.log('A Pawn has been promoted!');
console.log(square);
});
// when an undo function is called on a move
gameClient.on('undo', (move) => {
console.log('A previous move was undone!');
console.log(move);
});
capture
EventThe capture
event is emitted when a piece has been captured during game play. The capture
event data is the same as the move object that is provided as a response to gameClient.move().
check
EventThe check
event is emitted for each attack on a King that occurs on the board. In the event a single move results in multiple pieces putting a King in check, multiple check
events will be emitted, one for each attack.
attack
ObjectThe attack object contains the attacking square and the King square. The properties of the attack object are:
{
attackingSquare : {
file: 'f',
rank: 6,
piece: {
moveCount: 3,
side: {
name: 'white'
},
type: 'knight',
notation: 'N'
}
},
kingSquare : {
file: 'e',
rank: 8,
piece: {
moveCount: 0,
side: {
name: 'black'
},
type: 'king',
notation: 'K'
}
}
}
checkmate
EventThe checkmate
event is emitted when checkmate has been detected on the board. The checkmate
event data is the same as the attack object that is provided for the check
event.
castle
EventThe castle
event is emitted when a castle move occurs on the board. The castle
event data is the move object that is also returned when performing a gameClient.move().
enPassant
EventWhen en Passant occurs, the enPassant
event is emitted. The enPassant
event data is the move object that is also returned when performing a gameClient.move().
move
EventAny time a move occurs on the board, the move
event is emitted. The enPassant
event data is the move object that is also returned when performing a gameClient.move().
promote
EventWhen a Pawn promotion occurs, the promote
event is emitted. The promote
event data is the Square object upon which the newly promoted piece resides, which looks as follows:
{
file: 'a',
piece: {
moveCount: 2,
notation: 'R',
side: {
name: 'white'
},
type: 'rook' },
rank: 8
}
undo
EventThe undo
event is emitted when a previous move that occured on the board is reversed using the undo
method. The undo
event data is the same move object that is also returned when performing a gameClient.move().
gameClient.move()
FunctionFrom the above example, the response object that is returned when calling chess.move() looks like the following:
{
move: {
// the captured piece (if capture occurred)
capturedPiece: null,
// was the move a castle?
castle: false,
// was the move en Passant?
enPassant: false,
// tje square a piece was moved to
postSquare: {
file: 'a',
rank: 4,
piece: {
moveCount: 1,
side: {
name: 'white'
},
type: 'pawn',
notation: 'R'
}
},
// the square that the piece came from
prevSquare: {
file: 'a',
rank: 2,
piece: null
}
},
// undo() can be used to back out the previous move
undo: __function__
}
move
ObjectThe move object contains a collection of properties and an undo function pointer. The five properties of the move object are:
undo()
FunctionTo back out the move:
move.undo();
gameClient.getStatus()
FunctionThe status object is as follows (abbreviated in parts to improve readability):
{
// this is the top level board
board: {
// an array of all squares on the board
squares: [{
file: 'a',
rank: 1,
piece: {
moveCount: 0,
side: {
name: 'white'
},
type: 'rook',
notation: 'R'
}
},
/* the rest of the squares... */
]
},
isCheck: false, // is the King currently in check?
isCheckmate: false, // is the King currently in checkmate?
isRepetition: false, // has 3-fold repetition occurred?
isStalemate: false, // is the board in stalemate?
// all possible moves (notated) with details for each move
notatedMoves: {
a3: {
src: {
file: 'a'
rank: 2,
piece: {
moveCount: 0,
side: {
name: 'white'
},
type: 'pawn',
notation: 'R'
}
},
dest: {
file: 'a',
rank: 3,
piece: null
}
},
/* the rest of the available moves... */
}
}
status
ObjectThe status object returned via the getStatus() function call contains several Object properties:
status.notatedMoves
ObjectEach object within the notatedMoves hash represents a possible move. The key to the hash is the algebraic notation of the move. The value for each key in the hash has two properties:
The following code is an example of how to iterate the available notated moves for the game.
import chess from 'chess';
const gameClient = chess.create();
let
i = 0,
key = '',
status = gameClient.getStatus();
Object.keys(status.notatedMoves).map((key, index) => {
console.log(status.notatedMoves[key]);
return { ...status.notatedMoves[key], key };
});
The following usage of the code is playing out the 3rd game in the series between Fischer and Petrosian in Buenos Aires, 1971. The game ended a draw due to 3 fold repetition.
import chess from 'chess';
const util = require('util');
const gameClient = chess.create();
// 1. e4 e6
gameClient.move('e4');
gameClient.move('e6');
// 2. d4 d5
gameClient.move('d4');
gameClient.move('d5');
// 3. Nc3 Nf6
gameClient.move('Nc3');
gameClient.move('Nf6');
// 4. Bg5 dxe4
gameClient.move('Bg5');
gameClient.move('dxe4');
// 5. Nxe4 Be7
gameClient.move('Nxe4');
gameClient.move('Be7');
// 6. Bxf6 gxf6
gameClient.move('Bxf6');
gameClient.move('gxf6');
// 7. g3 f5
gameClient.move('g3');
gameClient.move('f5');
// 8. Nc3 Bf6
gameClient.move('Nc3');
gameClient.move('Bf6');
// 9. Nge2 Nc6
gameClient.move('Nge2');
gameClient.move('Nc6');
// 10. d5 exd5
gameClient.move('d5');
gameClient.move('exd5');
// 11. Nxd5 Bxb2
gameClient.move('Nxd5');
gameClient.move('Bxb2');
// 12. Bg2 O-O
gameClient.move('Bg2');
gameClient.move('0-0');
// 13. O-O Bh8
gameClient.move('0-0');
gameClient.move('Bh8');
// 14. Nef4 Ne5
gameClient.move('Nef4');
gameClient.move('Ne5');
// 15. Qh5 Ng6
gameClient.move('Qh5');
gameClient.move('Ng6');
// 16. Rad1 c6
gameClient.move('Rad1');
gameClient.move('c6');
// 17. Ne3 Qf6
gameClient.move('Ne3');
gameClient.move('Qf6');
// 18. Kh1 Bg7
gameClient.move('Kh1');
gameClient.move('Bg7');
// 19. Bh3 Ne7
gameClient.move('Bh3');
gameClient.move('Ne7');
// 20. Rd3 Be6
gameClient.move('Rd3');
gameClient.move('Be6');
// 21. Rfd1 Bh6
gameClient.move('Rfd1');
gameClient.move('Bh6');
// 22. Rd4 Bxf4
gameClient.move('Rd4');
gameClient.move('Bxf4');
// 23. Rxf4 Rad8
gameClient.move('Rxf4');
gameClient.move('Rad8');
// 24. Rxd8 Rxd8
gameClient.move('Rxd8');
gameClient.move('Rxd8');
// 25. Bxf5 Nxf5
gameClient.move('Bxf5');
gameClient.move('Nxf5');
// 26. Nxf5 Rd5
gameClient.move('Nxf5');
gameClient.move('Rd5');
// 27. g4 Bxf5
gameClient.move('g4');
gameClient.move('Bxf5');
// 28. gxf5 h6
gameClient.move('gxf5');
gameClient.move('h6');
// 29. h3 Kh7
gameClient.move('h3');
gameClient.move('Kh7');
// 30. Qe2 Qe5
gameClient.move('Qe2');
gameClient.move('Qe5');
// 31. Qh5 Qf6
gameClient.move('Qh5');
gameClient.move('Qf6');
// 32. Qe2 Re5
gameClient.move('Qe2');
gameClient.move('Re5');
// 33. Qd3 Rd5
gameClient.move('Qd3');
gameClient.move('Rd5');
// 34. Qe2
gameClient.move('Qe2');
console.log(util.inspect(gameClient.getStatus(), false, 7));
The above code produces the following output:
{
board: {
squares: [
{ file: 'a', rank: 1, piece: null },
{ file: 'b', rank: 1, piece: null },
{ file: 'c', rank: 1, piece: null },
{ file: 'd', rank: 1, piece: null },
{ file: 'e', rank: 1, piece: null },
{ file: 'f', rank: 1, piece: null },
{ file: 'g', rank: 1, piece: null },
{ file: 'h',
rank: 1,
piece:
{ moveCount: 2,
side: { name: 'white' },
type: 'king',
notation: 'K' } },
{ file: 'a',
rank: 2,
piece:
{ moveCount: 0,
side: { name: 'white' },
type: 'pawn',
notation: '' } },
{ file: 'b', rank: 2, piece: null },
{ file: 'c',
rank: 2,
piece:
{ moveCount: 0,
side: { name: 'white' },
type: 'pawn',
notation: '' } },
{ file: 'd', rank: 2, piece: null },
{ file: 'e',
rank: 2,
piece:
{ moveCount: 6,
side: { name: 'white' },
type: 'queen',
notation: 'Q' } },
{ file: 'f',
rank: 2,
piece:
{ moveCount: 0,
side: { name: 'white' },
type: 'pawn',
notation: '' } },
{ file: 'g', rank: 2, piece: null },
{ file: 'h', rank: 2, piece: null },
{ file: 'a', rank: 3, piece: null },
{ file: 'b', rank: 3, piece: null },
{ file: 'c', rank: 3, piece: null },
{ file: 'd', rank: 3, piece: null },
{ file: 'e', rank: 3, piece: null },
{ file: 'f', rank: 3, piece: null },
{ file: 'g', rank: 3, piece: null },
{ file: 'h',
rank: 3,
piece:
{ moveCount: 1,
side: { name: 'white' },
type: 'pawn',
notation: '' } },
{ file: 'a', rank: 4, piece: null },
{ file: 'b', rank: 4, piece: null },
{ file: 'c', rank: 4, piece: null },
{ file: 'd', rank: 4, piece: null },
{ file: 'e', rank: 4, piece: null },
{ file: 'f',
rank: 4,
piece:
{ moveCount: 4,
side: { name: 'white' },
type: 'rook',
notation: 'R' } },
{ file: 'g', rank: 4, piece: null },
{ file: 'h', rank: 4, piece: null },
{ file: 'a', rank: 5, piece: null },
{ file: 'b', rank: 5, piece: null },
{ file: 'c', rank: 5, piece: null },
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
{ file: 'e', rank: 5, piece: null },
{ file: 'f',
rank: 5,
piece:
{ moveCount: 3,
side: { name: 'white' },
type: 'pawn',
notation: '' } },
{ file: 'g', rank: 5, piece: null },
{ file: 'h', rank: 5, piece: null },
{ file: 'a', rank: 6, piece: null },
{ file: 'b', rank: 6, piece: null },
{ file: 'c',
rank: 6,
piece:
{ moveCount: 1,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
{ file: 'd', rank: 6, piece: null },
{ file: 'e', rank: 6, piece: null },
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
{ file: 'g', rank: 6, piece: null },
{ file: 'h',
rank: 6,
piece:
{ moveCount: 1,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
{ file: 'a',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
{ file: 'b',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
{ file: 'c', rank: 7, piece: null },
{ file: 'd', rank: 7, piece: null },
{ file: 'e', rank: 7, piece: null },
{ file: 'f',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
{ file: 'g', rank: 7, piece: null },
{ file: 'h',
rank: 7,
piece:
{ moveCount: 2,
side: { name: 'black' },
type: 'king',
notation: 'K' } },
{ file: 'a', rank: 8, piece: null },
{ file: 'b', rank: 8, piece: null },
{ file: 'c', rank: 8, piece: null },
{ file: 'd', rank: 8, piece: null },
{ file: 'e', rank: 8, piece: null },
{ file: 'f', rank: 8, piece: null },
{ file: 'g', rank: 8, piece: null },
{ file: 'h', rank: 8, piece: null }
],
},
isCheck: false,
isCheckmate: false,
isRepetition: true,
isStalemate: false,
notatedMoves:
{ Rd4:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 4, piece: null } },
Rd3:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 3, piece: null } },
Rd2:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 2, piece: null } },
Rd1:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 1, piece: null } },
Rd6:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 6, piece: null } },
Rd7:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 7, piece: null } },
Rd8:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'd', rank: 8, piece: null } },
Rc5:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'c', rank: 5, piece: null } },
Rb5:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'b', rank: 5, piece: null } },
Ra5:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'a', rank: 5, piece: null } },
Re5:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest: { file: 'e', rank: 5, piece: null } },
Rxf5:
{ src:
{ file: 'd',
rank: 5,
piece:
{ moveCount: 4,
side: { name: 'black' },
type: 'rook',
notation: 'R' } },
dest:
{ file: 'f',
rank: 5,
piece:
{ moveCount: 3,
side: { name: 'white' },
type: 'pawn',
notation: '' } } },
c5:
{ src:
{ file: 'c',
rank: 6,
piece:
{ moveCount: 1,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'c', rank: 5, piece: null } },
Qxf5:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest:
{ file: 'f',
rank: 5,
piece:
{ moveCount: 3,
side: { name: 'white' },
type: 'pawn',
notation: '' } } },
Qe6:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'e', rank: 6, piece: null } },
Qd6:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'd', rank: 6, piece: null } },
Qg6:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'g', rank: 6, piece: null } },
Qe7:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'e', rank: 7, piece: null } },
Qd8:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'd', rank: 8, piece: null } },
Qg5:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'g', rank: 5, piece: null } },
Qh4:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'h', rank: 4, piece: null } },
Qe5:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'e', rank: 5, piece: null } },
Qd4:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'd', rank: 4, piece: null } },
Qc3:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'c', rank: 3, piece: null } },
Qb2:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'b', rank: 2, piece: null } },
Qa1:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'a', rank: 1, piece: null } },
Qg7:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'g', rank: 7, piece: null } },
Qh8:
{ src:
{ file: 'f',
rank: 6,
piece:
{ moveCount: 3,
side: { name: 'black' },
type: 'queen',
notation: 'Q' } },
dest: { file: 'h', rank: 8, piece: null } },
h5:
{ src:
{ file: 'h',
rank: 6,
piece:
{ moveCount: 1,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'h', rank: 5, piece: null } },
a6:
{ src:
{ file: 'a',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'a', rank: 6, piece: null } },
a5:
{ src:
{ file: 'a',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'a', rank: 5, piece: null } },
b6:
{ src:
{ file: 'b',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'b', rank: 6, piece: null } },
b5:
{ src:
{ file: 'b',
rank: 7,
piece:
{ moveCount: 0,
side: { name: 'black' },
type: 'pawn',
notation: '' } },
dest: { file: 'b', rank: 5, piece: null } },
Kh8:
{ src:
{ file: 'h',
rank: 7,
piece:
{ moveCount: 2,
side: { name: 'black' },
type: 'king',
notation: 'K' } },
dest: { file: 'h', rank: 8, piece: null } },
Kg7:
{ src:
{ file: 'h',
rank: 7,
piece:
{ moveCount: 2,
side: { name: 'black' },
type: 'king',
notation: 'K' } },
dest: { file: 'g', rank: 7, piece: null } },
Kg8:
{ src:
{ file: 'h',
rank: 7,
piece:
{ moveCount: 2,
side: { name: 'black' },
type: 'king',
notation: 'K' } },
dest: { file: 'g', rank: 8, piece: null } } } }
FAQs
An algebraic notation driven chess engine that can validate board position and produce a list of viable moves (notated).
The npm package chess receives a total of 47 weekly downloads. As such, chess popularity was classified as not popular.
We found that chess demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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