//创建一个Cookie
function writeCookie()
{
 
  var destoryTime = new Date();
 
  destoryTime.setTime(destoryTime.getTime()+24*3600*1000);

  var expireTime = destoryTime.toGMTString();

  document.cookie = "vistited=true"+";expires="+expireTime+";";

  document.write("<div id='tip'>欢迎首次光临sky论坛，5秒之后您返回论坛首页。。</div>");

  setTimeout("backToMainPage()",5000);
}

function backToMainPage()
{
  window.loaction.href = "http://bbs.blueidea.com/";
}

var isCookieExist;

IsCookieExist = doucment.cookie.length;

if(!isCookieExist)
   writeCookie();
else
{
 var cookieContent = document.cookie;

 var checkStatus = "visited=";
 
 var startIndex = cookieContent.indexOf(checkStatus);

 if(startIndex !=-1)
 {
   startIndex += checkStatus.length;
  
   var endIndex = cookieContent.indexOf(",",startIndex);
  
   if(endIndex ==-1)
  
    endIndex = cookieContent.length;
    
    var result = unescape(cookieContent.substring(startIndex,endIndex));

    if(result != "true")
       writeCookie();
       else
       document.write("<div id='tip'>欢迎再次来到本论坛</div>")
  
 }else
  writeCookie();
}

• cookie