js動畫特效 =====在頁面滾動

html:
<div id="news">
    <ul>
        <li><a href="#" title="aaaaaaaaaaaaaaa">aaaaaaaaaaaaaaa</a></li>
        <li><a href="#" title="bbbbbbbbbbbbbbb">bbbbbbbbbbbbbbb</a></li>
        <li><a href="#" title="ccccccccccccccc">ccccccccccccccc</a></li>
        <li><a href="#" title="ddddddddddddddd">ddddddddddddddd</a></li>
        <li><a href="#" title="eeeeeeeeeeeeeee">eeeeeeeeeeeeeee</a></li>
        <li><a href="#" title="fffffffffffffff">fffffffffffffff</a></li>
        <li><a href="#" title="ggggggggggggggg">ggggggggggggggg</a></li>
    </ul>
</div>

css:

ui,li {
     height: 10px;
     line-height: 10px;
     list-style: none;
}
#news{
    height: 75px;
    overflow: hidden;
}

jQuery:

$(function() {
    var $this = $("#news");
    var scrollTimer;
    $this.hover(function() {
        clearInterval(scrollTimer);
    }, function() {
        scrollTimer = setInterval(function() {
            scrollNews($this);
        }, 2000);
    }).trigger("mouseleave");

    function scrollNews(obj) {
        var $self = obj.find("ul");
        var lineHeight = $self.find("li:first").height(); 
        $self.animate({
            "marginTop": -lineHeight + "px"
        }, 600, function() {
            $self.css({
                marginTop: 0
            }).find("li:first").appendTo($self);
        })
    }
})