javascript 延时显示层 DEMO

代码

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"/>
<title>无标题文档</title>
<script language="javascript" type="text/javascript">
var MaxNum =3
var n=0;
var showNum = document.getElementById("num");

//设置哪个div要显示(根据div 的id)
function plays(value)
{
for(i=0;i<=MaxNum;i++)
{
var divlist = document.getElementById("NewsPic"+ i);
if(divlist ==null)//js判断对象是否存在
{
return;
}
else
{
if(i == value)
{
divlist.style.display="block";
}
else
{
divlist.style.display="none";
}
}
}
}

//设置轮换时间 js设置延时
function setAuto(){autoStart=setInterval("auto(n)", 2000)}

//判断div id是否超出最大或者不存在某个对象
function auto()
{
n++;
if(n > MaxNum || document.getElementById("NewsPic"+ n) ==null)
{
n =0;
}
plays(n);
}

//初始运行
setAuto();

</script>

</head>

<body>
<div id="NewsPic0" style="display:block;">div格式自己调,这里放想放的内容 id为NewsPic0</div>
<div id="NewsPic1" style="display:none;">div格式自己调,这里放想放的内容 id为NewsPic1</div>
<div id="NewsPic2" style="display:none;">div格式自己调,这里放想放的内容 id为NewsPic2</div>
<div id="NewsPic3" style="display:none;">div格式自己调,这里放想放的内容 id为NewsPic3</div>

</body>
</html>