<span id="imgArea"></span>
<SCRIPT LANGUAGE="JavaScript">
<!--
function setCookie(name,value)
{
var Days = 30; //此 cookie 将被保存 30 天
var exp = new Date(); //new Date("December 31, 9998");
exp.setTime(exp.getTime() + Days*24*60*60*1000);
document.cookie = name + "="+ escape(value) +";expires="+ exp.toGMTString();
}
function getCookie(name)
{
var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
if(arr != null) return unescape(arr[2]); return null;
}
function delCookie(name)
{
var exp = new Date();
exp.setTime(exp.getTime() - 1);
var cval=getCookie(name);
if(cval!=null) document.cookie=name +"="+cval+";expires="+exp.toGMTString();
}
window.onload = function()
{
var n = getCookie("DoNotShowImage");
if(!n)
{
document.getElementById("imgArea").innerHTML = "<img alt='' src='http://www.csdn.net/Images/logo_csdn.gif'/>";
setCookie("DoNotShowImage", "true");
}
else delCookie("DoNotShowImage");
}
//-->
</SCRIPT>
<SCRIPT LANGUAGE="JavaScript">
<!--
function setCookie(name,value)
{
var Days = 30; //此 cookie 将被保存 30 天
var exp = new Date(); //new Date("December 31, 9998");
exp.setTime(exp.getTime() + Days*24*60*60*1000);
document.cookie = name + "="+ escape(value) +";expires="+ exp.toGMTString();
}
function getCookie(name)
{
var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
if(arr != null) return unescape(arr[2]); return null;
}
function delCookie(name)
{
var exp = new Date();
exp.setTime(exp.getTime() - 1);
var cval=getCookie(name);
if(cval!=null) document.cookie=name +"="+cval+";expires="+exp.toGMTString();
}
window.onload = function()
{
var n = getCookie("DoNotShowImage");
if(!n)
{
document.getElementById("imgArea").innerHTML = "<img alt='' src='http://www.csdn.net/Images/logo_csdn.gif'/>";
setCookie("DoNotShowImage", "true");
}
else delCookie("DoNotShowImage");
}
//-->
</SCRIPT>
.....//ad codes
}
else{
}
你只需要随机生成1/0,因为根据统计学,在一定流量下,始终会接近50 50