Detect and fire scrollDown & scrollUp events

jScroll.js

(function($) {
    // ## Detect and fire scrollDown & scrollUp events
    var lastScrollTop = $(window).scrollTop();
    $(window).scroll(function(){
        var current = $(this).scrollTop();
        // Check the direction of the scroll
        if (current >= lastScrollTop){
            // Trigger the down scroll event
            $(this).trigger('jScroll.down');
            // Detect a change of direction
            if($(this).data('jScroll.direction')) {
                // then trigger a scroll direction change event
                $(this).trigger('jScroll.direction.change');
            }
            // set the scroll direction into the jQuery object data
            $('body').removeClass('scrollup');
            $('body').addClass('scrollDown');
            $(this).data('jScroll.direction', -1);
        }
        else {
            // Trigger the up scroll event
            $(this).trigger('jScroll.up');
            if(!$(this).data('jScroll.direction')) {
                $(this).trigger('jScroll.direction.change');
            }
            $('body').removeClass('scrollDown');
            $('body').addClass('scrollup');
            $(this).data('jScroll.direction', 1);
        }
        // reset lastScrollTop
        lastScrollTop = current;
    });
})(jQuery);