Fill input with Function javascript result

Question

I am using the following function to validate CNPJ in Input:

function FormataCnpj(campo, teclapres) {
    var tecla = teclapres.keyCode;
    var vr = new String(campo.value);
    vr = vr.replace(".", "");
    vr = vr.replace("/", "");
    vr = vr.replace("-", "");
    tam = vr.length + 1;
    if (tecla != 14) {
        if (tam == 3)
            campo.value = vr.substr(0, 2) + '.';
        if (tam == 6)
            campo.value = vr.substr(0, 2) + '.' + vr.substr(2, 5) + '.';
        if (tam == 10)
            campo.value = vr.substr(0, 2) + '.' + vr.substr(2, 3) + '.' + vr.substr(6, 3) + '/';
        if (tam == 15)
            campo.value = vr.substr(0, 2) + '.' + vr.substr(2, 3) + '.' + vr.substr(6, 3) + '/' + vr.substr(9, 4) + '-' + vr.substr(13, 2);
    }
}



function validarCNPJ(cnpj) {

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

    if (cnpj == '') return false;

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

    // 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;

    // Valida DVs
    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;


    return true;
}

calls her that way:

<input ID="txCNPJ_cad_emp" name="cnpj" class="form-control" placeholder="Digite o CNPJ" onkeyup="FormataCnpj(this,event)" onblur="if(!validarCNPJ(this.value)){alert('CNPJ Informado é inválido'); this.value='';}" required autofocus></>

If the CNPJ is invalid it returns an Alert to me, but instead of displaying an Alert I need it to change another input

<input ID="txCNPJ_cad_emp" name="cnpj">

putting the error message in it: "Invalid CNPJ".

Answer 1

Replaces Alert by field value assignment:

<input ID="txCNPJ_cad_emp" name="cnpj" class="form-control" placeholder="Digite o CNPJ" onkeyup="FormataCnpj(this,event)" onblur="if(!validarCNPJ(this.value)){this.value = 'CNPJ inválido'; this.value='';}" required autofocus>

Note that in condition true is setting empty value this.value='';. That’s the way you want it?

Answer 2

I suggest removing the direct declared event return test in the element to make it better for you to view:

<input ID="txCNPJ_cad_emp" id="cnpj" name="cnpj" class="form-control" placeholder="Digite o CNPJ" onkeyup="FormataCnpj(this,event)" onblur="verificarValidacaoCNPJ()" required autofocus></>

I also changed the HTML a little to add an id, since both elements (inpt of cnpj and msg validation) have the same name.

Treatment in function called on onblur:

function verificarValidacaoCNPJ(){
    var valCNPJ = !document.getElementById("cnpj")? "" : document.getElementById("cnpj").value;
    if(!validarCNPJ(valCNPJ))
        document.getElementById("txCNPJ_cad_emp").value = "CNPJ inválido";
    else
        document.getElementById("txCNPJ_cad_emp").value = "CNPJ válido";
}