Checkbox attr checked

[joubert@…]

I did a test in my application and some features are not working on checkbox, see my log below firebug:

$("#lol");

Object[input#lol] /* Ok, my checkbox */

$("#lol").attr('checked');

undefined

[Checked in browser]

$("#lol").attr('checked');

undefined

$("#lol").attr('checked', 'checked');

Object[input#lol]

$("#lol").removeAttr('checked');

Object[input#lol] /* Works */

$("#lol").attr('checked', );

Object[input#lol]

$("#lol").attr('checked', null);

Object[input#lol] /* Works */

$("#lol").attr('checked', true);

Object[input#lol]

[dmethvin]

Duplicate of #13245.