CPF e CNPJ em JavaScript

function isValidCPF(cpf) {
  cpf = String(cpf).replace(/\D/g, '');
  if (cpf.length !== 11 || /^(\d)\1{10}$/.test(cpf)) return false;
  const dv = (slice) => {
    let sum = 0;
    for (let i = 0; i < slice.length; i++) sum += +slice[i] * (slice.length + 1 - i);
    const rest = (sum * 10) % 11;
    return rest === 10 ? 0 : rest;
  };
  return dv(cpf.slice(0, 9)) === +cpf[9] && dv(cpf.slice(0, 10)) === +cpf[10];
}