Why does my CNPJ validation pass this invalid value?

Question

I have a problem with a JS validation, in case it does not pass any invalid CNPJ value, but when typed only 000.000.000/0000.00 it lets pass normally.

function ValidaCNPJ(cnpj) {

  var i = 0;
  var l = 0;
  var strNum = "";
  var strMul = "0000000000000";
  var character = "";
  var iValido = 1;
  var iSoma = 0;
  var strNum_base = "";
  var iLenNum_base = 0;
  var iLenMul = 0;
  var iSoma = 0;
  var strNum_base = 0;
  var iLenNum_base = 0;

  if (cnpj == "")
    return false;

  l = cnpj.length;
  for (i = 0; i < l; i++) {
    caracter = cnpj.substring(i,i+1)
    if ((caracter >= '0') && (caracter <= '9'))
       strNum = strNum + caracter;
  };

  if(strNum.length != 14)
    return false;

  strNum_base = strNum.substring(0,12);
  iLenNum_base = strNum_base.length - 1;
  iLenMul = strMul.length - 1;
  for(i = 0;i < 12; i++)
    iSoma = iSoma +
            parseInt(strNum_base.substring((iLenNum_base-i),(iLenNum_base-i)+1),10) *
            parseInt(strMul.substring((iLenMul-i),(iLenMul-i)+1),10);

  iSoma = 11 - (iSoma - Math.floor(iSoma/11) * 11);
  if(iSoma == 11 || iSoma == 10)
    iSoma = 0;

  strNum_base = strNum_base + iSoma;
  iSoma = 0;
  iLenNum_base = strNum_base.length - 1
  for(i = 0; i < 13; i++)
    iSoma = iSoma +
            parseInt(strNum_base.substring((iLenNum_base-i),(iLenNum_base-i)+1),10) *
            parseInt(strMul.substring((iLenMul-i),(iLenMul-i)+1),10)

  iSoma = 11 - (iSoma - Math.floor(iSoma/11) * 11);
  if(iSoma == 11 || iSoma == 10)
    iSoma = 0;
  strNum_base = strNum_base + iSoma;
  if(strNum != strNum_base) {
    return false
  }else{
    return true;
  }
}

window.onload = function (){
  var cnpj = document.getElementById('reg_billing_cnpj');

  cnpj.onblur = function(){
    var valid = ValidaCNPJ(this.value);
    if(valid == false){

      alert("Informe um CNPJ válido");
      cnpj.focus(); 
      return (false); 


    }
  }
}

Answer 1

Do it, buddy. It works perfectly for me:

function validarCNPJ(cnpj) {

    cnpj = cnpj.replace(/[^\d]+/g,'');

    if(cnpj == '') return false;

    if (cnpj.length != 14)
        return false;

    // LINHA 10 - Elimina CNPJs invalidos conhecidos
    if (cnpj == "00000000000000" || 
        cnpj == "11111111111111" || 
        cnpj == "22222222222222" || 
        cnpj == "33333333333333" || 
        cnpj == "44444444444444" || 
        cnpj == "55555555555555" || 
        cnpj == "66666666666666" || 
        cnpj == "77777777777777" || 
        cnpj == "88888888888888" || 
        cnpj == "99999999999999")
        return false; // LINHA 21

    // Valida DVs LINHA 23 -
    tamanho = cnpj.length - 2
    numeros = cnpj.substring(0,tamanho);
    digitos = cnpj.substring(tamanho);
    soma = 0;
    pos = tamanho - 7;
    for (i = tamanho; i >= 1; i--) {
      soma += numeros.charAt(tamanho - i) * pos--;
      if (pos < 2)
            pos = 9;
    }
    resultado = soma % 11 < 2 ? 0 : 11 - soma % 11;
    if (resultado != digitos.charAt(0))
        return false;

    tamanho = tamanho + 1;
    numeros = cnpj.substring(0,tamanho);
    soma = 0;
    pos = tamanho - 7;
    for (i = tamanho; i >= 1; i--) {
      soma += numeros.charAt(tamanho - i) * pos--;
      if (pos < 2)
            pos = 9;
    }
    resultado = soma % 11 < 2 ? 0 : 11 - soma % 11;
    if (resultado != digitos.charAt(1))
          return false; // LINHA 49

    return true; // LINHA 51

}

In cnpj = cnpj.replace(/[^\d]+/g,'');, we have deleted all non-numerical characters from the CNPJ passed as parameter, considering that whoever invoked the function may have used a possible mask in the field.

The if instruction in if (cnpj.length != 14)return false; checks whether the number number of the string (considering it already clean) is equal to the correct amount - 14.

The lines 10 to 21 check whether the string is formed only by equal values. This verification is necessary since if we apply the CNPJ algorithm on the number "22.222.222/2222-22" in theory the check digits are correct, even if this is NOT a valid number.

Lines 23 through 49 check the two check digits, verifying their validity according to the CNPJ algorithm. If no, the validation returns false by terminating the function.

If the algorithm reaches line 51 we have a valid CNPJ and the true value is returned.

Source: http://www.geradorcnpj.com/javascript-validar-cnpj.htm

Answer 2

There is a more compact function to validate CNPJ:

function is_cnpj(c) {
    var b = [6, 5, 4, 3, 2, 9, 8, 7, 6, 5, 4, 3, 2];

    if ((c = c.replace(/[^\d]/g, "")).length != 14)
        return false;

    if (/0{14}/.test(c))
        return false;

    for (var j = 0; j < 2; ++j) {
        for (var i = 0, n = 0; i < 12 + j; n += c[i] * b[++i - j]);
        if (c[12 + j] != ((n %= 11) < 2) ? 0 : 11 - n)
            return false;
    }

    return true;
};

You can test the operation and validation on the link http://araujo.cc/blog/funcao-javascript-para-validar-cnpj.html

Answer 3

Just adding a bit of improvement to the @Lollipop response, just below the explanation:

function validarCNPJ(cnpj) {
	
    if(cnpj == '' || cnpj == undefined || cnpj == null) {
        return false;
    }
	
    if (typeof(cnpj) != 'string') {
	cnpj = cnpj.toString();
    }
	
    cnpj = cnpj.replace(/[^\d]+/g,'');
  
    // (Restante ok...)

I did tests with the function by passing different parameters such as arrays, objects or Numbers. As errors occurred, I decided to increment a little the initial part of the algorithm in the parameter validation:

1. Check first of all if the value is empty, undefined or null. There is no need to do anything before that, nor to let go.
2. Check if the parameter is different from a string (may have come a number, array, Object, etc.)
3. Converts to string, after all cnpj may have been passed as number, and it is necessary for the . replace() method below to work correctly
4. Now apply replace() and proceed

I apologize for not being able to comment directly on his reply, I use little Stackoverflow and my low reputation still does not allow.

I hope it will be useful. Hugs to all!

Answer 4

Although there is no CNPJ or CPF with all digits repeated, the official logic of validating the check digit of these documents declares them as valid.

Note that not only a sequence of zeros will pass but also a sequence of one or of two or of any digit.

The way is, in addition to implementing the official algorithm, to include a if invalidating the document if all digits are equal.

Some ways to do this:

function todosDigitosSaoIguais(cnpj) {
    var cnpj_arr = cnpj.split("");
    var first = cnpj_arr[0];
    return cnpj_arr.every(function(element) {
        return element === first;
    });
}

Or:

function todosDigitosSaoIguais(cnpj) {
    for(var i = 1; i < cnpj.length; i++)
    {
        if(cnpj[i] !== cnpj[0])
            return false;
    }
    return true;
}