(function($){
	$.belowthefold=function(element,settings){
		var fold=$(window).height()+$(window).scrollTop();
		return fold<=$(element).offset().top-settings.threshold;
	};
	$.abovethetop=function(element,settings){
		var top=$(window).scrollTop();
		return top>=$(element).offset().top+$(element).height()-settings.threshold;
	};
	$.rightofscreen=function(element,settings){
		var fold=$(window).width()+$(window).scrollLeft();
		return fold<=$(element).offset().left-settings.threshold;
	};
	$.leftofscreen=function(element,settings){
		var left=$(window).scrollLeft();
		return left>=$(element).offset().left+$(element).width()-settings.threshold;
	};
	$.inviewport=function(element,settings){
		return!$.rightofscreen(element,settings)&&!$.leftofscreen(element,settings)&&!$.belowthefold(element,settings)&&!$.abovethetop(element,settings);
	};
	$.extend($.expr[':'],{
		"below-the-fold":function(a,i,m){
			return $.belowthefold(a,{threshold:0});
		},"above-the-top":function(a,i,m){
			return $.abovethetop(a,{threshold:0});
		},"left-of-screen":function(a,i,m){
			return $.leftofscreen(a,{threshold:0});
		},"right-of-screen":function(a,i,m){
			return $.rightofscreen(a,{threshold:0});
		},"in-viewport":function(a,i,m){
			return $.inviewport(a,{threshold:0});
		}
	});
})(jQuery);