cpf-generator.js

class CPF {
  static CPF_MASK = '$1.$2.$3-$4';
  static CPF_REGEX = /(\d{3})(\d{3})(\d{3})(\d{2})/;

  static generateFormated() {
      return this.format(this.generate());
  }
  static format(cpf) {
      return cpf.replace(this.CPF_REGEX, this.CPF_MASK);
  }
  static removeFormatting(cpf) {
      return cpf.replace(/[-\.]/g, '');
  }
  static generate() {
      const randomNumber = (Math.random() * 1000000000).toString();
      const integerString = parseInt(randomNumber).toString();
      let _cpf = integerString.padStart(9, '0');
      for (let digit = 0; digit < 100; digit++) {
          const verifierDigit = digit.toString().padStart(2, '0');
          if (this.isValid(_cpf + verifierDigit))
              return _cpf += verifierDigit;
      }
      return _cpf;
  }
  static isValid(cpf) {
      const _cpf = this.removeFormatting(cpf);
      let sum = 0, rest;
      const ALL_DIGITS_ARE_THE_SAME = _cpf.split('')
          .every(digit => digit === _cpf[0]);
      if (ALL_DIGITS_ARE_THE_SAME)
          return false;
      for (let i = 1; i <= 9; i++)
          sum += parseInt(_cpf.substring(i - 1, i)) * (11 - i);
      rest = (sum * 10) % 11;
      if ((rest === 10) || (rest === 11))
          rest = 0;
      if (rest !== parseInt(_cpf.substring(9, 10)))
          return false;
      sum = 0;
      for (let j = 1; j <= 10; j++)
          sum += parseInt(_cpf.substring(j - 1, j)) * (12 - j);
      rest = (sum * 10) % 11;
      if ((rest == 10) || (rest == 11))
          rest = 0;
      if (rest != parseInt(_cpf.substring(10, 11)))
          return false;
      return true;
  }
}

console.log(CPF.generate());