var intervalId = null;
function slideAd(id,nStayTime,sState,nMaxHth,nMinHth){
    this.stayTime=nStayTime*1000 || 3000;
    this.maxHeigth=nMaxHth || 544 //广告最大高度
    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 +5 ) : (h - 5))+"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,2);
}