javascript实现的拉幕式广告，当页面打开时广告会缓缓打开，在制定时间之后再缓缓的收起到隐藏，代码很简洁也很实用已经封装好，制定id和时间后即可使用。
js代码部分：
<script type=”text/javascript”>
var intervalId = null;
function slideAd(id,nStayTime,sState,nMaxHth,nMinHth){
this.stayTime=nStayTime*1000 || 3000;
this.maxHeigth=nMaxHth || 260;
this.minHeigth=nMinHth || 1;
this.state=sState || “down” ;
var obj = document.getElementById(id);
if(intervalId != null)window.clearInterval(intervalId);
function openBox(){
var h = obj.offsetHeight;
obj.style.height = ((this.state == “down”) ? (h + 2) : (h – 2))+”px”;
if(obj.offsetHeight>this.maxHeigth){
window.clearInterval(intervalId);
intervalId=window.setInterval(closeBox,this.stayTime);
}
if (obj.offsetHeight<this.minHeigth){
window.clearInterval(intervalId);
obj.style.display=”none”;
}
}
function closeBox(){
slideAd(id,this.stayTime,”up”,nMaxHth,nMinHth);
}
intervalId = window.setInterval(openBox,10);
}
</script>
html部分：
<div id=”MyMoveAd” style=”height:12px;overflow:hidden;width:960px;margin:0px auto;”>
<a href=”http://events.cnw.com.cn/nww09/” target=”_blank”><img src=”http://www.cnw.cn/zhuanti/mail/20090819/nww_move.gif”/></a>
</div>
<script type=”text/javascript”>
slideAd(‘MyMoveAd’,6); //此处绑定id和时间
</script>
