Validador de CNPJ escrito em TypeScript

validateCNPJ.ts

const cnpjPattern = /^(\d{2}[-.\s]?\d{3}[-.\s]?\d{3}[-.\s/]?\d{4}[-.\s]?\d{2})$/

function calcDigit(cnpjArray: number[]) {
  const x = cnpjArray.length

  const { sum } = cnpjArray.reduce(
    (acc, curr) => ({
      sum: acc.sum + curr * acc.factor,
      factor: acc.factor > 2 ? acc.factor - 1 : 9,
    }),
    { sum: 0, factor: x - 7 },
  )

  const result = 11 - (sum % 11)

  return result > 9 ? 0 : result
}

const isSameDigit = (numbers: number[]) => [...new Set(numbers)].length === 1

export function validateCNPJ(cnpj: string) {
  if (!cnpjPattern.test(cnpj)) return false

  const cnpjArray = cnpj
    .replace(/[^\d]+/g, '')
    .split('')
    .map(Number)

  if (isSameDigit(cnpjArray)) return false

  const checkDigits = cnpjArray.slice(12)

  const firstDigit = calcDigit(cnpjArray.slice(0, 12))
  if (firstDigit !== checkDigits[0]) return false

  const secondDigit = calcDigit(cnpjArray.slice(0, 13))
  if (secondDigit !== checkDigits[1]) return false

  return true
}