// primary function to retrieve cookie by name
function GetCookie(name)
{
    var arg = name + "=";
    var alen = arg.length;
    var clen = document.cookie.length;
    var i = 0;
    while(i < clen)
    {
        var j = i + alen;
        if (document.cookie.substring(i, j) == arg)
        {
            return getCookieVal(j);
        }
        i = document.cookie.indexOf(" ", i) + 1;
        if(i == 0) break;
    }
    return;
}

// store cookie value with optional details as needed
function SetCookie(name,value){ 
 var argv=SetCookie.arguments;
 var argc=SetCookie.arguments.length;
 var expires=(2<argc)?argv[2]:null;
 var path=(3<argc)?argv[3]:null;
 var domain=(4<argc)?argv[4]:null;
 var secure=(5<argc)?argv[5]:false;
 document.cookie=name+"="+escape(value)+((expires==null)?"":("; expires="+expires.toGMTString()))+((path==null)?"":("; path="+path))+((domain==null)?"":("; domain="+domain))+((secure==true)?"; secure":"");
} 


// remove the cookie by setting ancient expiration date
function DeleteCookie(name,path,domain) 
{
    if(getCookie(name))
    {
        document.cookie = name + "=" +
            ((path) ? "; path=" + path : "") +
            ((domain) ? "; domain=" + domain : "") +
            "; expires=Thu, 01-Jan-70 00:00:01 GMT";
    }
}

//-----------------------------------HELPER---------------------------------------------//

// utility function to retrieve an expiration data in proper format;
function getExpDate(days, hours, minutes)
{
    var expDate = new Date();
    if(typeof(days) == "number" && typeof(hours) == "number" && typeof(hours) == "number")
    {
        expDate.setDate(expDate.getDate() + parseInt(days));
        expDate.setHours(expDate.getHours() + parseInt(hours));
        expDate.setMinutes(expDate.getMinutes() + parseInt(minutes));
        return expDate.toGMTString();
    }
}

//utility function called by getCookie()
function getCookieVal(offset)
{
    var endstr = document.cookie.indexOf(";", offset);
    if(endstr == -1)
    {
        endstr = document.cookie.length;
    }
    return unescape(document.cookie.substring(offset, endstr));
}
    
//编码程序
function CodeCookie(str)
{
　var strRtn="";

　for (var i=str.length-1;i>=0;i--)
　{
　　strRtn+=str.charCodeAt(i);
　　if (i) strRtn+="a"; //用a作分隔符
　}
　return strRtn;
}


//解码程序：
function DecodeCookie(str)
{
　var strArr;
　var strRtn="";

　strArr=str.split("a");

　for (var i=strArr.length-1;i>=0;i--) 
　strRtn+=String.fromCharCode(eval(strArr[i]));

　return strRtn;
}