为了练习javascript，做了一个简单的demo，实现的是广告从顶部慢慢拉出到最大，然后停留2s，再收缩到比较小且可以关闭的广告特效。图片可以替换为任意其他的图片。
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<style>
#ad{
width:962px;
display:none;
margin:0 auto;
overflow:hidden;
position:relative;
}
#main{
margin:0 auto;
width:960px;
height:1700px;
}
#close{
width:20px;
height:20px;
position:absolute;
top:0;
right:0;
font-size:16px;
line-height:20px;
text-align:center;
display:none;
background:yellowgreen;
}
</style>
</head>
<body>
<div id="ad">
<img src="ad.png" id="imgAd" width="962" height="386">
<img src="cur.png" id="curAd" width="1199" height="68">
<span id="close">x</span>
</div>
<div id="main"><img src="数字商品-10-23.jpg"></div>
<script>
var oImgAd=document.getElementById('imgAd');
var oad=document.getElementById('ad');
var ocur=document.getElementById('curAd');
var closeBtn=document.getElementById('close');
var h=0;
var maxH=oImgAd.height;
var minH=ocur.height;
function down()
{
if(h<maxH)
{
h+=5;
oad.style.height=h+"px";
oad.style.display="block";
setTimeout(down,5);
}
else{
setTimeout(up,2000);
}
}
function up(){
if(h>minH){
h-=5;
oad.style.height=h+"px";
setTimeout(up,5);
}
else{
oImgAd.style.display='none';
closeBtn.style.display='block';
}
}
closeBtn.onclick=function(){
oad.style.display='none';
}
setTimeout(down,1000);
</script>
</body>
</html>