Super simple jQuery slider I created the most simple though still quite flexible jQuery slider ever! Or at least, I hope so.

var slider = $(".slider-ul");

slider.each(function () {

    var e = $(this),
        images = e.find("li"),
        current = null;

    slide();

    function slide() {

        images.each(function() {

            var li = $(this),
                next,
                pDone = false,
                sDone = false;

            if (li.hasClass("primary")) {
                li.removeClass("primary");
                pDone = true;
            } else if (li.hasClass("secondary")) {
                li.removeClass("secondary").addClass("primary");

                next = li.next();

                console.log(next);
                if (next.size()) {
                    next.addClass("secondary");
                    sDone = true;
                } else {
                    images.filter(":first").addClass("secondary");
                    sDone = true;
                }
            }

            if (sDone &amp;&amp; pDone) {
                return false;
            }
        });

        setTimeout(slide, 5000);

    }
});


How does this look?
In this code, you set sDone = true in both branches of the if-else:


if (next.size()) {
    next.addClass("secondary");
    sDone = true;
} else {
    images.filter(":first").addClass("secondary");
    sDone = true;
}



So you could move that line outside of the if-else:

if (next.size()) {
    next.addClass("secondary");
} else {
    images.filter(":first").addClass("secondary");
}
sDone = true;




At the top you declared the current variable,
but then you don't use it. If you don't need it, then remove it.