Can't use $.fn.add to add more elements into a cached jQuery object containing DOM elements.

If this works as intended, then at least the documentation on http://api.jquery.com/add/ is not clear about this, and then why shouldn't it be allowed?

I stumbled into this when I wanted to use .add() inside a loop to add an element into a collection, if certain criteria is fulfilled. The jQuery object containing the elements that fulfilled the criteria would be processed later.

Test code:

var d = $('div');
alert('divs: '+d.length);

// using add(), this failed
d = $();
$.each($('div'), function() {
  d.add(this);
});
alert('divs, using add() in a loop: '+d.length);

// workaround
d = [];
$.each($('div'), function() {
  d.push(this);
});
alert('divs, using array workaround: '+$(d).length);