jquery filtering has + not

Question

Okay I have list items, some have a span, some not.
On my event I want to add the span when they don\'t have any yet.

has() works fine, but

Answer 1

You can use a combination of the :not and :has selectors like this

$("a.add-span").click(function() {
    $("li:not(:has(span))").each(function(index) {
        $(this).append('new span<\/span>');
    });
});

Here is a demo http://www.jsfiddle.net/xU6fV/