jquery文字上下滚动的实现方法

//上下滚动
var textRoll=function(){
$('#notice p:last').css({'height':'0px','opacity': '0'}).insertBefore('#notice p:first').animate({'height':'35px','opacity': '1'}, 'slow', function() { $(this).removeAttr('style');});
                               }
$(function(){
//触发上下文字滚动事件
var roll=setInterval('textRoll()',4000);
$("#notice p").hover(function() {
                                clearInterval(roll);
                             }, function() {
                                 roll = setInterval('textRoll()', 4000)
                            });
            });