(function($) { $.fn.jScroll = function(e) { var f = $.extend({}, $.fn.jScroll.defaults, e); return this.each(function() { var a = $(this); var b = $(window); var c = new location(a); b.scroll(function() { a.stop().animate(c.getMargin(b), f.speed) }) }); function location(d) { this.min = d.offset().top; this.originalMargin = parseInt(d.css("margin-top"), 10) || 0; this.getMargin = function(a) { var b = d.parent().height() - d.outerHeight(); var c = this.originalMargin; if (a.scrollTop() >= this.min) c = c + f.top + a.scrollTop() - this.min; if (c > b) c = b; return ({ "marginTop": c + 'px' }) } } }; $.fn.jScroll.defaults = { speed: "slow", top: 10} })(jQuery);