Update content only when accessing div

Question

I have a step-by-step form from which every step saved in the database the information. In the last step I bring the information saved as follows with jquery:

<script type="text/javascript">
function mostrar(){   
    $(document).ready(function(){                      
            $.ajax({               
                    type:'post', 
                    dataType: 'json',
                    url: 'atualizar.php',
                    success: function(dados){

                       for(var i=0;dados.length>i;i++){
                           $('#listar').append(dados[0]);
                           $('#listar').append(dados[i].id+'</td><td>'+dados[i].nome+'</td><td>'+dados[i].email+'</td></tr>');
                       }

                    console.log(dados);    
                    }
            });
    });   
}
setInterval(mostrar, 2000);
</script>

It is working perfectly, but in this case I am updating for 02 seconds the div and I would like to know if it is possible to update only when accessing the div in the last step. HTML is that way:

<fieldset>
    <!-- Última etapa do step-by-step -->
    <h4>Confirme seus dados:</h4>

    <div id="listar"></div>

    <form role="form" action="" method="post" id="contact-form">
    <div class="f1-buttons">
        <button type="button" class="btn btn-previous">Alterar</button>
        <button type="button" class="btn btn-primary">Finalizar</button>
    </div>
    </form>
</fieldset>

Answer 1

You can know when you are at the last step by checking whether on fieldset active there is a button with the text "Finish". This check is done in the function below:

function scroll_to_class(element_class, removed_height) {
    var scroll_to = $(element_class).offset().top - removed_height;
    if($(window).scrollTop() != scroll_to) {
        $('html, body').stop().animate({scrollTop: scroll_to}, 0);
    }
   if( $('fieldset:visible').find('button:contains("Finalizar")').length == 1){
      // última etapa. Faça o que deseja aqui
      alert("Última etapa");
   }
}

Answer 2

Ideally you create a function that identifies when you are in a form with the Focus option.

When editing, do not update.

And as for saving the data, I imagine it is better to save in session or cookie and only at the end fill the comic.

This will prevent bank memory wear from bringing you performance, always think about it.