index.js

function handleSpecialCodes(nirpp) {
  if (nirpp.indexOf('A') !== -1) {
    return {
      withoutLetters: nirpp.replace('A', '0'),
      offset: 1000000,
    };
  }

  if (nirpp.indexOf('B') !== -1) {
    return {
      withoutLetters: nirpp.replace('B', '0'),
      offset: 2000000,
    };
  }

  return {
    withoutLetters: nirpp,
    offset: 0,
  };
}

function parse(nirpp) {
  const { withoutLetters, offset } = handleSpecialCodes(nirpp);
  return parseInt(withoutLetters, 10) - offset;
}

function generateControlKey(nirpp) {
  return 97 - (parse(nirpp) % 97);
}

function clean(nirpp) {
  return nirpp.toUpperCase().replace(/\s+/g, '');
}

function validCq(input, options = {}) {
  if (typeof input !== 'string') throw new TypeError('Input should be a string');
  const { shouldClean } = options;
  const cleanedInput = shouldClean === false ? input : clean(input);
  const key = cleanedInput.slice(-2);
  const withoutKey = cleanedInput.slice(0, -2);
  const computedKey = generateControlKey(withoutKey);
  return computedKey == key;
}

module.exports = { validate: validCq };