pgn-parser

Javascript library to allow reading of a PGN (Portable Game Notation) chess game notation, and providing the result as JSON.

What is it?

PGN is a shortcut for portable game notation. It was developed in 1993. It helps standardize how chess games were notated, so that computer programs like the PgnViewerJS could be developed. PGN is the standard to keep chess games forever. There are huge databases available like those from https://lichess.org.

Who needs it?

Everyone that wants to implement chess software and has to read PGN notation. The library is a runtime component to be included in the usual way.

import { parse } from '@mliebelt/pgn-parser'

or

let parse = require("@mliebelt/pgn-parser").parse

How to install it?

npm i @mliebelt/pgn-parser --save

How to use it?

Look at the many test cases that show how to use it. Have a look at the examples in directory doc.

It does not have an API, just a JSON structure that has to be read then. You have 4 top level rules to use the parser:

• games: Reads many games from the string given, returns an array of games (object with keys tags and moves).
• game: Reads a complete game, and returns an object with keys tags and moves.
• tags: Reads only the tags from the given input. The input must not contain any moves.
• pgn: Reads only the moves of the game (as array).

A code example to read a complete game then looks like:

import { parse } from '@mliebelt/pgn-parser'
let game = parse('[White "Me"] [Black "Magnus"] 1. f4 e5 2. g4 Qh4#', {startRule: "game"})
console.log(JSON.stringify(game, null, 2))

This leads to the following output:

{
  "tags": {
    "White": "Me",
    "Black": "Magnus"
  },
  "moves": [
    {
      "turn": "w",
      "moveNumber": 1,
    ...
    },
    {...},
    ...
  ]
}

See the example doc/read-sample.js that can be directly used in the shell: node doc/read-sample.js. The directory contains some more examples how to use it.

How to use it as an CLI?

You can use pgn-parser as a command line tool for parsing PGN files to JSON

npm install --global @mliebelt/pgn-parser
pgn-parser file.pgn

# Or

npx @mliebelt/pgn-parser file.pgn

The optional parameter -p emits the result pretty-printed.

How to use it in the browser?

There is a UMD version of the library available which works both in node and in the browser. The file doc/index.html is an example that shows how it works, and explains what to do for that.

So it is not necessary anymore to build a version of that library with browserify.

References

• peggy Parser Generator implemented in Javascript. Used for regenerating the javascript library completely by an automatic build.
• PGN Specification: PGN (Portable Game Notation) specification, there the section 8.2. Most other parts of the spec are implemented as well.
• PGN Supplement Additional specification for adding structured comments, like circles, arrows and clock annotations.
• NAG Specification Definition of the NAGs (Numeric Annotation Glyphs)