//写cookies函数
function SetCookie(name,value)//两个参数，一个是cookie的名子，一个是值
{
    if(getCookie(name)!=null)delCookie(name);
    var Hour = 3; //此 cookie 将被保存 3 小时
    var exp  = new Date();    //new Date("December 31, 9998");
    exp.setTime(exp.getTime() + Hour*60*60*1000);
    document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}
function getCookie(name)//取cookies函数       
{
    var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
     if(arr != null) return unescape(arr[2]); return null;

}
function delCookie(name)//删除cookie
{
    var exp = new Date();
    exp.setTime(exp.getTime() - 1);
    var cval=getCookie(name);
    if(cval!=null) document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}


function getContext(url){ 
   var index = url.indexOf("/",6); 
    if(index==-1){ return url;
  }
  var index2 = url.indexOf("/",index+1);
   return index2==-1?url.substring(index+1):url.substring(index+1,index2);
   
//var url = "http://search.cn.yahoo.com/photos/fengjing/index.html";
//alert(getContext(url)); 
 
}