Validador de CPF com TypeScript.

validateCPF.ts

const cpfPattern = /^(\d{11}|\d{3}\.\d{3}\.\d{3}-\d{2})$/

export function validateCPF(value: string): boolean {
  if (!value.match(cpfPattern)) return false

  // Remove caracteres especiais e espaços
  const unformattedCpf = value.replace(/[^A-z\d][\\^\s]?/g, '')

  // Separa os dígitos verificadores do parâmetro
  const checkDigits = unformattedCpf
    .slice(9, 11)
    .split('')
    .map(item => Number(item))

  // Primeiro dígito verificador
  // Estima o primeiro
  const firstDigitSum = unformattedCpf
    .slice(0, 9)
    .split('')
    .reduce(
      (accumulator, currentNumber, index) =>
        accumulator + Number(currentNumber) * (10 - index),
      0,
    )

  const firstDigitRest = firstDigitSum % 11
  const firstDigit = firstDigitRest > 2 ? 11 - firstDigitRest : 0

  if (checkDigits[0] !== firstDigit) return false

  // Segundo dígito verificador
  const secondDigitSum = unformattedCpf
    .slice(0, 10)
    .split('')
    .reduce(
      (accumulator, currentNumber, index) =>
        accumulator + Number(currentNumber) * (11 - index),
      0,
    )

  const secondDigitRest = secondDigitSum % 11
  const secondDigit = secondDigitRest > 2 ? 11 - secondDigitRest : 0

  if (checkDigits[1] !== secondDigit) return false

  return true
}