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Introduction

Chessops is a powerful TypeScript library that provides chess and chess variant rules and operations. It offers a type-safe, efficient implementation of chess logic using bitboards and modern TypeScript features.

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Key features

Chessops provides everything you need to work with chess positions, moves, and games:
  • Type-safe position representation - Uses bitboards (SquareSet) for efficient board state management
  • FEN/PGN/SAN notation support - Parse and write standard chess notations
  • Legal move generation - Generate all legal moves for any position
  • Chess variants - Support for 8 variants: Standard chess, Crazyhouse, King of the Hill, Three-check, Antichess, Atomic, Horde, and Racing Kings
  • Streaming PGN parser - Process large PGN files with denial-of-service resistant streaming
  • Attack calculations - Fast attack and ray computations using Hyperbola Quintessence
  • Position validation - Validate chess positions and detect illegal setups
  • Board transformations - Mirror and rotate positions
  • Chess960 support - Full support for Chess960/Fischer Random Chess

Installation

Get started with npm, yarn, or pnpm

Quick start

Learn the basics in 5 minutes

API reference

Explore the full API documentation

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Example

Here’s a simple example showing how to parse a FEN position and check for checkmate: 
import { Chess } from 'chessops/chess';
import { parseFen } from 'chessops/fen';

const setup = parseFen('r1bqkbnr/ppp2Qpp/2np4/4p3/2B1P3/8/PPPP1PPP/RNB1K1NR b KQkq - 0 4').unwrap();
const pos = Chess.fromSetup(setup).unwrap();
console.assert(pos.isCheckmate());
Chessops uses the Result type from @badrap/result for error handling. Use .unwrap() to extract values or handle errors explicitly.

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Core concepts

Chessops is built around a clear vocabulary of types:
  • Square - A square on the chess board (0-63)
  • SquareSet - A set of squares implemented as bitboards for efficiency
  • Color - 'white' or 'black'
  • Role - Piece type: 'pawn', 'knight', 'bishop', 'rook', 'queen', 'king'
  • Piece - Combination of role and color
  • Board - Map of piece positions
  • Setup - A position that may not be legal
  • Position - Base class for legal positions
  • Chess - Concrete implementation for standard chess positions

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Next steps

Install chessops

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Quick start guide

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