How can I get the id in classes with equal names?

When you have a selector that returns more than one element, and you call the html method on it, it only returns the result of the first element. Several jQuery functions work the same way.

If you want the contents of all the elements (in a list, for example), you can use the .map function. :

$('span.brand-id.hidden').map(function() {
    return $(this).html();
});

Example in jsFiddle . The result is an array-like that you can save or use in a for normal (i.e. using length , accessing elements as lista[0] etc).

Try to make a function to check a property of the element itself (removing unnecessary html code), something like (I removed span hidden with value in html and set a value to name ):

<div class="quest-alternatives">
<p class="brand-alternative">

<span class="radio-button brand-id" name="123" id="brand-0"></span>
<label for="brand-0" class="brand-name">Opção 0</label></p>

<p class="brand-alternative">

<span class="radio-button brand-id" name="456" id="brand-1"></span>
<label for="brand-1" class="brand-name">Opção 1</label></p>

<p class="brand-alternative">

<span class="radio-button brand-id" name="789" id="brand-2"></span>
<label for="brand-2" class="brand-name">Opção 2</label></p></div>

JQuery should be this:

$('.brand-id').each(function(index, value){
 var id = $(this).attr("id"); // retorna brand-0/brand-1/brand-2
 var valor = $(this).attr("name"); // retorna 123/456/789
 alert(id + "-" + valor);
});

Here's the JSFiddle with the code.