chess-fen

chess-fen is a library which includes tools for working with Forsyth–Edwards Notation (FEN) in an immutable manner.

Installation

npm install chess-fen

Version 1.0.0+

Since 1.0.0 chess-fen is no longer also a standard notation parser and instead focuses on being a simple data structure with basic primitives for working with FEN notation. This means the previous Fen.move() method has been removed along with associated classes, types and functions for working with parsing chess moves.

There have also been some significant changes to the types ( https://github.com/cymantex/chess-fen/blob/master/src/module/types.ts).

Example usage

const emptyPosition = new Fen(Fen.emptyPosition);

//Each update() creates a new Fen instance.
const smotheredMate = emptyPosition
  .update("h8", PIECES.k)
  .update("h7", PIECES.p)
  .update("g7", PIECES.p)
  .update("e8", PIECES.r)
  .update("a8", PIECES.q)
  .update("g5", PIECES.N)
  .update("c4", PIECES.Q)
  .update("h2", PIECES.K);

smotheredMate.printBoard();
// -------------------
// | q . . . r . . k |
// | . . . . . . p p |
// | . . . . . . . . |
// | . . . . . . N . |
// | . . Q . . . . . |
// | . . . . . . . . |
// | . . . . . . . K |
// | . . . . . . . . |
// -------------------

// The original Fen will not be mutated
emptyPosition.printBoard();
// -------------------
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// | . . . . . . . . |
// -------------------

API

Constructor: Fen(fenOrArgs?: string | FenArgs)

The constructor takes an optional parameter which specifies the FEN board position.

const startingPosition = new Fen();

console.log(startingPosition.toString());
// rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

console.log(new Fen("rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2").toString());
// rnbqkbnr/pp1ppppp/8/2p5/4P3/8/PPPP1PPP/RNBQKBNR w KQkq c6 0 2

console.log(new Fen(Fen.emptyPosition).toString());
// 8/8/8/8/8/8/8/8 w KQkq - 0 1

get(Coordinate|Position)

Gets the content of the specified position.

const startingPosition = new Fen();

console.log(startingPosition.get("e1"));
// K

console.log(startingPosition.get("e4"));
// empty

console.log(startingPosition.get("k9"));
// null

// You can also send the x and y as a Position.
console.log(startingPosition.get(new Position(4, 7)));
// white king

clear(Coordinate|Position)

Removes the content on the specified position if there is any.

console.log(new Fen().clear("e1").toString());
// "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQ1BNR w KQkq - 0 1"

update(Coordinate|Position, BoardContent)

Replaces the content of the specified position.

console.log(new Fen().update("e1", BoardContent.BlackBishop).toString());
// rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQbBNR w KQkq - 0 1

isOccupied(Coordinate|Position)

const startingPosition = new Fen();

console.log(startingPosition.isOccupied("e2"));
// true

console.log(startingPosition.isOccupied("e4"));
// false

isEmpty(Coordinate|Position)

const startingPosition = new Fen();

console.log(startingPosition.isEmpty("e2"));
// false

console.log(startingPosition.isEmpty("e4"));
// true

Properties

console.log(new Fen(Fen.startingPosition));
// Fen {
//   rows: 8,
//   columns: 8,
//   board: [
//     ['r', 'n', 'b', 'q', 'k', 'b', 'n', 'r'],
//     ['p', 'p', 'p', 'p', 'p', 'p', 'p', 'p'],
//     [' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '],
//     [' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '],
//     [' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '],
//     [' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '],
//     ['P', 'P', 'P', 'P', 'P', 'P', 'P', 'P'],
//     ['R', 'N', 'B', 'Q', 'K', 'B', 'N', 'R']
//   ],
//   toMove: 'white',
//   castlingRights: {
//     white: { queenside: true, kingside: true },
//     black: { queenside: true, kingside: true }
//   },
//   enPassantSquare: '-',
//   halfMoves: 0,
//   fullMoves: 1
// }