$(
	function()
	{
		/* Newsslider */
		function slide(e)
		{
			$('#newsslider img:not(#active)').hide();
			var imgs = $("#newsslider").children('img');
			var pos = imgs.index(imgs.filter('#active'));
			if(e === "Up")
			{
				var next = (pos === 0) ? (imgs.size() - 1) : (pos - 1);
			}
			else if(e === "Down")
			{
				var next = (pos === (imgs.size() - 1)) ? 0 : (pos + 1);
			}
			$("#active").
				animate({opacity:"hide"}, {duration:2000, queue:false}).
				removeAttr("id");
			$("#newsslider").
				children().
				eq(next).
				animate({opacity:"show"}, {duration:2000, queue:false}).
				attr("id", "active");
		}
		$("#slideUp")
			.attr("href", "javascript: void(0)")
			.click(
				function(e)
				{
					slide("Up");
					return false;
				}
			)
		;
		$("#slideDown")
			.attr("href", "javascript: void(0)")
			.click(
				function(e)
				{
					slide("Down");
					return false;
				}
			)
		;
	}
);
<div id="newsslider">
	<a id="slideUp" href="./start.html3">rauf</a>
		<img id="active" src="./img/newsslider/0.jpg" />
		<img src="./img/newsslider/1.jpg" />
		<img src="./img/newsslider/2.jpg" />
		<img src="./img/newsslider/3.jpg" />
	<a id="slideDown" href="./start.html1">runter</a>
</div>