In short, the problem is that the following two lines do not select the same elements, even though as far as I understand, they should.

$("select option[selected=selected]")

$("option[selected=selected]", $("select"))

The fist correctly matches option elements where the "selected" attribute has the value of "selected", whereas the second does not match *any* elements.

I also notice that the "[selected]" attribute does not actually match the element that has an attribute with the name of "selected", but rather is equivalent to the ":selected" selector. This is rather inconsistent and seems undocumented.