codigo generador de CUIT javascript - CUIT generator

getCUIT.js

/**
 * Given a DNI and a gender it returns the corresponding CUIT.
 * @param {String} dni
 * @param {String} gender
 */
const getCUIT = (dni, gender = 'M') => {
  if (!dni || dni.length !== 8) {
    throw new Error('The DNI number must contain 8 numbers');
  }

  let genderNumber = gender === 'M' ? 20 : 27;

  const generateDigitVerificator = () => {
    const multipliers = [2, 3, 4, 5, 6, 7];
    const genderNumberAndDNI = `${genderNumber}${dni}`;

    let total = 0;
    let multipliersIndex = 0;
    for (let i = String(genderNumberAndDNI).length - 1; i > -1; i--) {
      const sum = genderNumberAndDNI[i] * multipliers[multipliersIndex];
      total += sum;
      if (multipliersIndex === 5) multipliersIndex = 0;
      else multipliersIndex += 1;
    }

    const digitVerificator = 11 - (total % 11);

    if (digitVerificator === 10) {
      genderNumber = 23;
      return generateDigitVerificator();
    }
    if (digitVerificator === 11) return 0;
    return digitVerificator;
  };

  const digitVerificator = generateDigitVerificator();

  return `${genderNumber}${dni}${digitVerificator}`;
};

module.exports = { getCUIT };

// https://es.wikipedia.org/wiki/Clave_%C3%9Anica_de_Identificaci%C3%B3n_Tributaria