JQuery data selector not updating with .data

jQuery .data() is initially populated with values from the data- attributes, but setting it only stores the associated new value in memory. It doesn't change the attribute in the DOM. To change the attribute, you have to use:

$('#one, #three').attr('data-test', 'changed');

The docs are at http://api.jquery.com/jQuery.data/

That's because i think that .data() use a special cache object inside jQuery to store data (in fact you can evens store object or complex tipes of data), if you check all the attributes are unchanged. If you want to change the attribute, use attr()