Validar CPF e CNPJ - Javascript ES6

validateCPF_CNPJ.js

/**
  @author github.com/mhef
*/

const validateCPF = (cpf) => {
  if (cpf.length != 11) return false;
  let expanded = [...cpf];
  let expandedWC = expanded.slice(0,9); // without check digits

  if(expanded.every(v => v == cpf[0])) return false; // fail if all numbers are equal

  let firstSum = expandedWC.reduce((acc, cur, idx) => acc + ((10-idx) * parseInt(cur)), 0);
  let firstDigit = ((firstSum % 11) < 2 ? 0 : 11 - (firstSum % 11));

  let expandedWF = [...expandedWC, firstDigit]; // with first digit

  let secondSum = expandedWF.reduce((acc, cur, idx) => acc + ((11-idx) * parseInt(cur)), 0);
  let secondDigit = ((secondSum % 11) < 2 ? 0 : 11 - (secondSum % 11));

  return firstDigit == expanded[9] && secondDigit == expanded[10];
}

const validateCNPJ = (cnpj) => {
  let weights = [6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2];

  if (cnpj.length != 14) return false;
  let expanded = [...cnpj];
  let expandedWC = expanded.slice(0,12); // without check digits

  if(expanded.every(v => v == cnpj[0])) return false; // fail if all numbers are equal

  let firstSum = expandedWC.reduce((acc, cur, idx) => acc + (weights[idx+1] * parseInt(cur)), 0);
  let firstDigit = ((firstSum % 11) < 2 ? 0 : 11 - (firstSum % 11));

  let expandedWF = [...expandedWC, firstDigit]; // with first digit

  let secondSum = expandedWF.reduce((acc, cur, idx) => acc + (weights[idx] * parseInt(cur)), 0);
  let secondDigit = ((secondSum % 11) < 2 ? 0 : 11 - (secondSum % 11));

  return firstDigit == expanded[12] && secondDigit == expanded[13];
}

validador de CPF quebrou o galho aqui, obrigado por compartilhar! :)