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JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.

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    Validation Identification document

    Asked by consultoriahalcon on June 06, 2017 at 06:16 AM



    I need to validate a field. The identification document. Is it possible to incluide Function script to validate this field??

    How should I incluide the function? o how could i do it?


    <script language="javascript"> 

    function validarFormatoDni(dni) {

    //alert('validando dni:' + dni + '...')


    if (dni!='')


    //alert('dni no vacio')

    dni = dni.toUpperCase();

    //alert('despues de poner en mayusculas')

      numero = dni.substr(0,dni.length-1);

    //alert('despues de quedarme con el numero')

     let = dni.substr(dni.length-1,1);

    //alert('despues de quedarme con la letra')

      numero = numero % 23;



     if (letra!=let)

        return false;


        return true;



    function validarDni(campo){


    if (!validarFormatoDni(campo.value)){

    alert("DNI/NIF incorrecto");







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    JotForm Support

    Answered by candy on June 06, 2017 at 08:00 AM


    Unfortunately, we do not offer programming support.

    Also, it is not possible to inject JavaScript codes to a form. 

    Thank you.