Using jQuery's .add method

Question

Either I am making a very silly mistake here, or there is a bug with jQuery's .add method. Most likely the former.

I am trying to implement a list of items that could be selected. Here's my code on jsfiddle.

The test case that is failing is the following:

1. Click the first element to select it.
2. Ctrl-click the second element to select it too.
3. Then click the third element (without Ctrl).

Now, I'd expect the first and second to be de-selected, I believe the implementation also does this. But the second one does not get de-selected.

Digging a little, it seems that the .add is actually not adding my elements to the jQuery object set and for the life of me, I can't figure out why.

Any suggestions on this? Or is this not the way the .add method is supposed to be used?

Edit: I know jquery-ui has a control for this kind of thing, but I have already evaluated it and it does not work for me. Thanks.

Answer 1

.add returns a new jQuery object, so you need to grab the value returned.

prevSelections = prevSelections.add(...);

Here's some other cleanup applied:

var ps = $(),
    clazz = 'selected';
$('#list').delegate('li', 'click', function(e) {
    if (e.ctrlKey) {
        ps = ps.add($(this).toggleClass(clazz));
    } else {
        if (ps.length) {
            ps.removeClass(clazz);
        }
        ps = $(this).addClass(clazz);
    }
});

Demo: http://jsfiddle.net/mattball/mAPQA/