Chess Validator

A Node.js command-line tool for validating chess positions and moves using FEN (Forsyth–Edwards Notation) notation.

Features

• Parse and validate FEN strings
• Display chess positions in ASCII format
• Make and validate chess moves
• Track game state including:
  • Current player's turn
  • Castling rights
  • En passant possibilities
  • Move counters
• Interactive command-line interface
• Support for standard chess notation

Installation

1. Ensure you have Node.js installed on your system
2. Clone this repository or create a new directory
3. Create the required files:
   • chessValidator.js
   • index.js
4. Install dependencies:

npm init -y

Usage

1. Start the program:

node index.js

2. Enter a FEN string when prompted. For example, use the starting position:

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

3. Available commands:
   • Enter moves in the format e2e4
   • Type board to display current position
   • Type fen to input a new position
   • Type exit to quit

FEN Format Explanation

FEN strings consist of six fields, separated by spaces:

1. Piece placement
2. Active color (w or b)
3. Castling availability
4. En passant target square
5. Halfmove clock
6. Fullmove number

Example FEN fields explained:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
|                                        | | |  | | |
Piece placement -------------------------+ | |  | | |
Active color (white) ---------------------+ |  | | |
Castling availability ---------------------+  | | |
En passant target square -------------------+ | |
Halfmove clock -------------------------------+ |
Fullmove number -------------------------------+

Piece Notation

• White pieces: K(King), Q(Queen), R(Rook), B(Bishop), N(Knight), P(Pawn)
• Black pieces: k(King), q(Queen), r(Rook), b(Bishop), n(Knight), p(Pawn)
• Empty squares: Numbers 1-8 representing consecutive empty squares

Example Session

Enter FEN position (or 'exit' to quit):
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

Current position:
  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

Enter move (e.g., e2e4):
e2e4

Made move! New position:
  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 . . . . 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

Features In Detail

Move Validation

• Basic piece movement rules
• Pawn promotion
• Castling (kingside and queenside)
• En passant captures
• Move counting
• Turn tracking

Board Display

• ASCII representation of the chess board
• Current position display
• Move history tracking
• Clear piece representation

Error Handling

• Invalid FEN detection
• Illegal move prevention
• Input validation
• Clear error messages

Limitations

• Does not validate check or checkmate
• Basic move validation only
• No move suggestion or analysis
• No game save/load functionality
• No PGN support

Contributing

Feel free to submit issues and enhancement requests. gh

License

This project is licensed under the MIT License - see the LICENSE file for details.