@echecs/san

Parse, resolve, and stringify SAN (Standard Algebraic Notation) chess moves. Strict TypeScript. Implements the notation defined in FIDE Laws of Chess, Appendix C.

Installation

npm install @echecs/san

Usage

import { parse, resolve, stringify } from '@echecs/san';

// Parse SAN syntax only — returns a SanMove (no position needed)
const sanMove = parse('Nf3');

// Parse and resolve in one call — returns a Move with from/to squares
const move = parse('Nf3', position);

// Resolve a SanMove to a Move (find the from square)
const move = resolve(sanMove, position);

// Convert a Move back to a SAN string
const san = stringify(move, position);

API

parse(san: string): SAN

Parses a SAN string and returns a SAN object describing the move's syntax. Does not require a position. Throws RangeError for empty or invalid input.

parse(san: string, position: Position): Move

Parses and resolves a SAN string against a position in one call. Equivalent to calling parse then resolve. Throws RangeError for empty, invalid, or illegal input.

resolve(move: SAN, position: Position): Move

Finds the source square for a SAN move in the given position. Throws RangeError if no legal move matches or if the move is ambiguous.

stringify(move: Move, position: Position): string

Returns the SAN string for a Move in the given position, including disambiguation, capture marker, check, and checkmate symbols. Throws RangeError if no piece occupies the source square.

Types

interface SAN {
  capture: boolean;
  castling: boolean;
  check: boolean;
  checkmate: boolean;
  from: Disambiguation | undefined;
  long: boolean;
  piece: Piece;
  promotion: PromotionPiece | undefined;
  to: Square | undefined;
}

from is the disambiguation hint from the SAN string (a file, rank, or full square), not the origin square. to is undefined for castling moves.

Move and PromotionPieceType are re-exported from @echecs/position. PromotionPiece is an alias for PromotionPieceType.

interface Move {
  from: Square;
  promotion?: PromotionPieceType;
  to: Square;
}

import type { Move, Position, PromotionPieceType, SAN } from '@echecs/san';

Errors

All functions throw RangeError for domain violations:

Situation	Message
Empty SAN string	Empty SAN string
Invalid SAN syntax	Invalid SAN: "<input>"
No legal move found	Describes the move
Ambiguous move	Lists the number of candidates
No piece on source square	Describes the square

License

MIT