Formatting mask for Brazilian CPF, CNPJ and CEP

formatMask.js

/**
 * @param {String} str - a string to be formatted.
 * @param {String} msk - 'CNPJ', 'CPF' or 'CEP' used in Brazil.
 */
function formatMask(str, msk) {
  var a = str.replace(/[^\d]+/g, ''); // remove non digit chars.
  switch (msk) {
  case "CNPJ":
    a = a.replace(/(\d{2})(\d{3})(\d{3})(\d{4})(\d{2})/, '$1.$2.$3/$4-$5');
    break;
  case "CPF":
    a = a.replace(/(\d{3})(\d{3})(\d{3})(\d{2})/, '$1.$2.$3-$4');
    break;
  case "CEP":
    a = a.replace(/(\d{5})(\d{3})/, '$1-$2');
    break;
  default:
    break;
  }
  return a;
}