Question

I search a simple/clean way to get every element with the same classes than a selected element.

something like that (not working)

var myElement = $("#elementId");

var listSameClass = $.hasClass(myElement.attr("class"));

Answer 1

I’d suggest, if I understand properly:

var currentClass = this.className,
    allWithClass = $('.' + className);

This does assume that a single class is present, however.

For elements with multiple classes:

var classes = this.className.split(/\s+/).join('.'),
    allWithClass = $('.' + classes);

Somehow I’d not realised that you were selecting an element by its id first, in that situation I’d advise you use Matt’s answer, since any correction would essentially turn my answer into a duplicate. Oops.