Polyglot is a node module to search moves in polyglot format opening books. For a description of the polyglot book format refer to this link.

Make sure you have node.js installed. Then do:

$ npm install polyglot-chess

var Polyglot = require('polyglot-chess');

var obj = new Polyglot();

var fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1";
console.log("Polyglot hash for fen " + fen + " is: " + obj.hash(fen));
console.log("Best move in the book is: " + obj.find(fen, "book.bin", true));
console.log("Random move in the book is: " + obj.find(fen, "book.bin", false));

Polyglot exposes following functions -

find takes a fen string and a book file path and looks up the hash in the book file. If findBest is true it returns the best move according to the weight otherwise it returns a random move with the given hash. The chance of a random move being returned is in proportion to its weight. If no move is found it returns an empty string.

hash takes a fen string and returns its polyglot hash.

To lint the js files with jshint run the command:

$ grunt lint

To run the tests with mocha run the command:

$ grunt test

Fork, pick an issue to fix from issues or add a missing feature and send a pull request.

This work is derivative of the excellent stockfish polyglot book source code.

Polyglot is released under the MIT License. See the bundled LICENSE file for details.