Validate CNPJ

validateCNPJ.js

export default function validateCNPJ(cnpj) {
    if (cnpj == '') return false
    if (cnpj.length != 14) return false
    if (cnpj == "00000000000000" ||
        cnpj == "11111111111111" ||
        cnpj == "22222222222222" ||
        cnpj == "33333333333333" ||
        cnpj == "44444444444444" ||
        cnpj == "55555555555555" ||
        cnpj == "66666666666666" ||
        cnpj == "77777777777777" ||
        cnpj == "88888888888888" ||
        cnpj == "99999999999999") return false;
    let size = cnpj.length - 2
    let numbers = cnpj.substring(0, size)
    let digits = cnpj.substring(size)
    let sum = 0
    let pos = size - 7
    for (let i = size; i >= 1; i--) {
        sum += numbers.charAt(size - i) * pos--
        if (pos < 2) pos = 9
    }
    let result = sum % 11 < 2 ? 0 : 11 - sum % 11
    if (result != digits.charAt(0)) return false
    size = size + 1
    numbers = cnpj.substring(0, size)
    sum = 0
    pos = size - 7
    for (let i = size; i >= 1; i--) {
        sum += numbers.charAt(size - i) * pos--
        if (pos < 2) pos = 9
    }
    result = sum % 11 < 2 ? 0 : 11 - sum % 11
    if (result != digits.charAt(1)) return false
    return true
}