Chess Engine (TypeScript)

A lightweight chess engine written in TypeScript with a clear separation between move validation and move execution.

Current implementation supports full piece movement rules for all standard piece types and a standard board setup.

Current Features

• 8x8 board model with bounds-safe access (Board)
• Standard starting position setup (Setup.standard)
• Piece movement rules implemented for:
  • pawn
  • rook
  • knight
  • bishop
  • queen
  • king
• Turn-based move validation pipeline (MoveValidator)
  • source square contains a piece
  • piece color matches current player
  • destination is in the piece's legal move list
  • move cannot leave own king in check
• Atomic move execution service (MoveService)
  • updates board squares
  • updates moved piece position
  • supports basic capture handling
• Full special-move support
  • castling
  • en passant
  • promotion (defaults to queen if omitted)
• Game state checks
  • check detection
  • checkmate detection
  • stalemate detection
  • game end reason (checkmate or stalemate)
• Algebraic square parsing and formatting (algebraicToPosition, positionToAlgebraic)
• Move history logging in game flow (from->to string format)
• Terminal-friendly ASCII board rendering (Board.toAscii / Board.print)

Architecture

• Game: orchestrates game flow (start, move, turn switching, history)
• Setup: places all pieces on initial squares
• MoveValidator: owns legality checks
• MoveService: owns state mutation for execute/undo
• Board: owns grid storage and square access
• Piece subclasses: own movement generation for each piece type
• utils: position and square conversion helpers

Project Structure

src/
  index.ts
  board/
    Board.ts
  game/
    Game.ts
    Setup.ts
  move/
    Move.ts
    MoveService.ts
    MoveValidator.ts
  pieces/
    Bishop.ts
    King.ts
    Knight.ts
    Pawn.ts
    Piece.ts
    Queen.ts
    Rook.ts
  types/
    grid.ts
    pieceType.ts
  utils/
    positionUtils.ts
    square.ts

tests/
  game/
    SpecialRules.test.ts
  pieces/
    Bishop.test.ts
    Pawn.test.ts
    RookKnight.test.ts
  utils/
    positionUtils.test.ts
    square.test.ts

Getting Started

Prerequisites

• Node.js 18+
• npm

Install

npm install

Run Demo

npm run dev

Run Tests

npm test

Watch Tests

npm run test:watch

Build

npm run build

Run Built Output

npm start

Usage Example

From src/index.ts:

import { Game } from "./game/Game";

const game = new Game();

game.start();
game.move("e2", "e4");
game.move("e7", "e5");
game.move("g1", "f3");
game.move("b8", "c6");
game.move("f1", "c4");

console.log("Game History:");
console.log(game.moveHistory);

console.log("Board State:");
game.board.print();

Current Limitations

• No FEN/PGN import-export
• Move history is a simple from->to list (not full algebraic notation)

License

This project is licensed under the ISC License. See LICENSE for details.