Deno-Chess

Deno dressed as a king

Deno-Chess is a speedy pure-Typescript chess engine. It is packaged for Deno, as well as for the browser. Features include:

Move generation / validation, piece logic, check / checkmate detection, draw detection, etc. All the standard Chess-engine stuff.
Can both read and write FEN strings.
Can both read and write PGN strings.
Fast! the game core is built on top of typed arrays, and a whole bunch of bit-math. In the end, it’s roughly 10x faster than Chess.js.

Example

import { ChessGame } from "https://deno.land/x/chess@0.2.1/mod.ts";

// Start a new game:
const game = ChessGame.NewStandardGame();

// Moves can be in UCI "{from}{dest}" format:
game.move("e2e4");

// ... Or in normal standard algebraic notation:
game.move("Nc6");

// Check if the game is over with:
game.isGameOver();
// => false

// Check the status of the game like so:
game.getStatus();
// => { state: "active", turn: "white" }

// Enumerate all moves available to the player with:
game.allMoves();
// => [ "b1a3", "b1c3", "d1e2", "d1f3", ... ]

// Do you want to render the board in text? Use .toString()
game.toString();
/*
    a  b  c  d  e  f  g  h
  +------------------------+
8 | r     b  q  k  b  n  r | 8
7 | p  p  p  p  p  p  p  p | 7
6 |       n                | 6
5 |                        | 5
4 |             P          | 4
3 |                        | 3
2 | P  P  P  P     P  P  P | 2
1 | R  N  B  Q  K  B  N  R | 1
  +------------------------+
    a  b  c  d  e  f  g  h
*/

// .toString() also lets you output in FEN:
game.toString("fen");
// => "r1bqkbnr/pppppppp/2n5/8/4P3/8/PPPP1PPP/RNBQKBNR w KQkq - 1 2"

Game API

Most of the game features are provided by the ChessGame class.

Starting a game

ChessGame.NewStandardGame()

Create a new chess game, in the standard setup.
ChessGame.NewFromFEN(fen: string)

Create a new chess game, using the provided FEN string as a starting point.
ChessGame.NewFromPGN(pgn: string)

Create a new chess game, using the provided PGN game as a starting point.

Playing a game

game.move(move: string, promotion?: string)

Performs a chess move.

The first “move” parameter can either be a short string in UCI (Universal Chess Interface) format, or a more human-friendly SAN (Standard Algebraic Notation) string.

The second “promotion” parameter is for when in UCI mode, so that a pawn that reaches its final rank can promote to the piece that it wants.
```
game.move("c7c8", "Q"); // Move to c8 ; Promote to Queen
```
The “promotion” parameter can be ignored when using SAN strings:
```
game.move("c8=Q");
```
If a pawn reaches its final rank, and a promotion piece wasn’t indicated, a ChessNeedsPromotion error is thrown.
game.allMoves(coord?: string)

Returns all available moves for the current player. If a coordinate is provided, only moves for the piece at that coord will be returned. If that space is either empty, or holds a piece that belongs to the other player, an empty array will be returned.

Moves are described as objects with these properties:
- from: The departure coordinate, in algebraic notation.
- dest: The destination coordinate, in algebraic notation.
- promotion: True when this is a pawn promotion, and will require that parameter when moving.
game.isGameOver()

Returns true if this game is over, and no further moves can be provided.
game.getStatus()

Returns an object that describes the game’s status. Has these properties:
- state: One of the following strings:
  - "active" - The game is still going
  - "checkmate" - The current player was checkmated.
  - "resigned" - A player resigned.
  - "draw-other" - A draw was declared, for some reason.
  - "draw-stalemate" - The current player is in stalemate: They have no moves available to them, but they aren’t in check.
  - "draw-repetition" - The game was drawn since the same board position came up 3 different times.
  - "draw-fifty-moves" - The game was drawn, since it’s been 50 full moves since the last capture or pawn advancement.
  - "draw-no-material" - The game was drawn, since there just isn’t enough material on the boart to deliver a checkmate.
- turn: Who’s turn is it to play? Either "white" or "black".
- winner: If the game is in a final (ie: not "active") state, this property will be included, and will be one of: "white", "black", or "draw".
- reason: If the game was drawn for some “other” reason, and that reason was provided, this property will be included to give that reason.
game.history()

Returns all moves in the game history.
game.resignGame(player: "white" | "black")

The given player has resigned the game, meaning that the OTHER player wins.
game.drawGame(reason?: string)

The game was drawn. A reason can be provided.

Outputting a string

game.toString(format = "ascii")

Will return the game as a string, in the given format. (Default is “ascii”)

"ascii" - A simple plain-text format.

____a  b  c  d  e  f  g  h
  +------------------------+
8 | r  n  b  q  k  b  n  r | 8
7 | p  p  p  p  p  p  p  p | 7
6 |                        | 6
5 |                        | 5
4 |                        | 4
3 |                        | 3
2 | P  P  P  P  P  P  P  P | 2
1 | R  N  B  Q  K  B  N  R | 1
  +------------------------+
    a  b  c  d  e  f  g  h

"terminal" - The same as ascii, but with ANSI color codes that make the output look cool in a terminal.

"fen" - Output in FEN format.

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

"pgn" - Output in PGN format.

[Event "Example game for \"README.md\""]
[Site "?"]
[Date "2021.06.11"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "1-0"]

1. e4 e5 2. Bc4 Bc5 3. Qf3 d6 4. Qxf7# 1-0

Adding AI

This project has a pretty easy (and kinda slow) AI, that is being casually worked on, but will probably never get too advanced. Still, if you want to try it out:

import { BeginnerAI, ChessGame } from "https://deno.land/x/chess@0.2.1/mod.ts";

const game = ChessGame.NewStandardGame();
const ai = BeginnerAI.NewForGame(game, "black");

// And whenever it's the AI's turn to play:
ai.takeTurn();

TODO:

Some things that I plan on getting to:

Slightly better AI.
Openings database. (Probably available as a separate module, to keep the main module size small.)
Ability to connect with UCI-compatible engines.

License

MIT