document.writeln("关闭
");
document.writeln("打开
");
document.writeln("");
var nowheight=0; //初始广告层高度
var maxheight=30; //广告层最大高度
var adobj;
var opendiv;
var closdiv;
var addfunc;
var handobj;
var reducefunc;
var speed=7; //层卷动速度
function showtopad() {
adobj=document.getElementById("bigad");
opendiv=document.getElementById("opendiv");
closdiv=document.getElementById("closdiv");
if (nowheight<=0) {
opendiv.style.display="none";
adobj.style.display="block";
addfunc=setInterval("addheight()",1);
}
}
function closetopad() {
if (nowheight>0) {
callreduceheight();
if (typeof(handobj)=="number") {
clearTimeout(handobj);
}
}
}
function addheight() {
nowheight+=speed;
if (nowheight>maxheight) {
clearInterval(addfunc);
closdiv.style.top=maxheight-30;
closdiv.style.display="block";
handobj=setTimeout("callreduceheight()",20000);
return;
}
adobj.style.height=nowheight+"px";
}
function callreduceheight() {
closdiv.style.display="none";
reducefunc=setInterval("reduceheight()",1);
}
function reduceheight() {
adobj.style.height=nowheight+"px";
nowheight-=speed;
if (nowheight<=0) {
clearInterval(reducefunc);
adobj.style.display="none";
opendiv.style.display="block";
return;
}
}
showtopad();