Compare the number of occurrences of an Array in Javascript dynamic fields before submitting form data

Question

How can I compare the number of occurrences of Array in dynamic fields Javascript before sending the form data. I need to check if both are equal. I can do it only after sending with the function Count of PHP, I would like to know if there is any way to do this before sending, and if possible, via Javascript, because it is already the validation of the form. How to count these values of the Array before sending?

Dynamic fields:

<script type="text/javascript">

    // Verificar se ambos Array tem o mesmo número de ocorrências 
    $(document).ready(function() {
    $("#mail_form").submit( function() {

        var qtdmyfoto = document.querySelectorAll('name="myfoto[]"').length;
        var qtdreferencia = document.querySelectorAll('name="referencia[]"').length;

        if(qtdmyfoto != qtdreferencia)
        {
        alert("Falta alguma coisa");
        return false;
        }   

    });

});
</script>

<form id="mail_form" role="form" action="">
       .
       .
       .
       .
   <script type="text/javascript"> 
       .
       .
       .
       .
   $(wrapper).append('<div>'
        +'<div>'
            +'<br><label class="control-label">Foto: '+z +'</label>'
            +'<input type="file"  name="myfoto[]"  /> '
        +'</div>'

        +'<div>'
            +'<br><label class="control-label">Referência Foto '+z +'</label>'
            +'<input type="text" class="form-control" name="referencia[]">'
        +'</div>'    
    +'</div>');
    </script>
</form>

I’m unsuccessfully trying something like:

$(document).ready(function() {
    $("#mail_form").submit( function() {

        if(referencia.array.length != myfoto.array.length)
        {
            alert("Falta alguma coisa");
            return false;
        }

    });

});