공지사항 자동롤링 질문드립니다

<!DOCTYPE html><html lang="ko"><head>	<meta charset="UTF-8">	<title>board</title>	<link rel="stylesheet" media="screen" />	<script src="http://code.jquery.com/jquery-1.10.1.min.js"></script>	<script src="http://code.jquery.com/jquery-migrate-1.2.1.min.js"></script>	<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-easing/1.3/jquery.easing.min.js"></script></head><style>*{padding:0; margin:0}.boardArea {width:100%; height:50px; overflow:hidden; background-color:#fff;}.boardList {position:relative; width:100%; height:auto;}.boardList li {width:100%; height:50px; line-height:50px;} .navBox {position:absolute; top:50px;}.more {position:absolute; top:100px;}  </style></head> <body> <div class="boardArea">	<div class="navBox">		<a href="" class="prev">이전</a>		<a href="" class="next">다음</a>	</div>	<ul class="boardList">		<li>			<a href="">11111111111111111</a>		</li>		<li>			<a href="">22222222222222222</a>		</li>		<li>			<a href="">33333333333333333</a>		</li>		<li>			<a href="">44444444444444444</a>		</li>		<li>			<a href="">55555555555555555</a>		</li>	</ul>	<a href="" class="more">더보기</a></div> </body> <script>$(document).ready(function(){	var $bardArea = $(".boardArea"),		$boardBox = $(".boardList"),		$boardList = $boardBox.find("li"),		$nav = $(".navBox"),			areaHeight =  $(".boardArea").height(),		listCount = $(".boardList li").length,		maxHeight = areaHeight * listCount,		currentIndex = 0,		duration = 500,		interval = 1000,		easing = "swing",		timer;		function rollingList(index){		$boardBox.animate({top:"-100" * index +"%"}, duration, easing);		currentIndex = index;	}		function startTimer () {		timer = setInterval(function(){			var nextIndex = currentIndex + 1;			if (nextIndex > listCount - 1){				nextIndex = 0;			} 			rollingList(nextIndex);		}, interval);	}	$boardBox.append($boardList.first().clone());	function stopTimer (){		clearInterval(timer);	}		$nav.on('click', 'a', function (event) {        event.preventDefault();        if ($(this).hasClass('prev')) {            rollingList(currentIndex - 1);        } else if ($(this).hasClass('next')) {            rollingList(currentIndex + 1);        } 		if (currentIndex < 0){			$boardBox.prepend($boardList.last().clone());		} else if (currentIndex > 4){			$boardBox.append($boardBox.find("li").clone());		}	});			$bardArea.on({		mouseenter: stopTimer,		mouseleave: startTimer	});		startTimer();		}); </script> </html>