jQuery onscreen / offscreen selector

jQuery onscreen or offscreen selector

$.expr[':'].onscreen = function(obj){
	obj = jQuery(obj)
	return obj.position().top < jQuery(window).height() && obj.position().top < jQuery(window).width();
};

$.expr[':'].offscreen = function(obj){
	obj = jQuery(obj)
	return obj.position().top > jQuery(window).height() && obj.position().top > jQuery(window).width();
};