parse.js

// Module import
const fs = require('fs');
const Parser = require('binary-parser').Parser;


const readComment = Parser.start().array('comment', {
  type: 'uint8',
  readUntil: function (a, b) {
    return b.readUInt16LE() === 0 || b.length < 3;
  },
  formatter: function (a) {
    return a.map(v => String.fromCharCode(parseInt(v, 10).toString(10))).join('');
  }
}).skip(2);

const readMove = Parser.start()
  .uint8('move', {
    formatter: (flag) => [flag % 16 - 1, Math.ceil(flag / 16) - 1]
  })
  .bit1('down') // 128  Has Siblings
  .bit1('right') // 64 Has a child node, into the subtree
  .bit1('hz4')
  .bit1('mark')
  .bit1('hasComment')
  .bit1('hz2')
  .bit1('hz1',)
  .bit1('extension')
  .choice('comment', {
      tag: 'hasComment',
      choices: {
        0: Parser.start(),
        1: readComment
      }
    }
  );


const header = Parser.start()
  .endianess('little')
  .uint8('open', {assert: 255})
  .string('type', {
    length: 6,
    assert: 'RenLib'
  })
  .uint8('open', {assert: 255})
  .int8('major', {assert: 3})
  .int8('minor')
  .skip(10);


p = new Parser()
  .nest('header', {
    type: header
  })
  .array('moves', {
    type: readMove,
    readUntil: 'eof'
  });

require('fs').readFile('ss.lib', function (err, data) {
  const v = p.parse(data);
  console.log(JSON.stringify(v));
  fs.writeFileSync('moves.json', JSON.stringify(v), 'UTF-8');

});