function setCookie(key, value, expiredays)
{
    var todayDate = new Date();
    todayDate.setDate(todayDate.getDate() + expiredays);
    document.cookie = key + "=" + escape(value) + "; expires=" + todayDate.toGMTString() + "; path=/";
}

function readCookie(key)
{
    var cookie = document.cookie;

    var first = cookie.indexOf(key + "=");

    if (first >= 0)
    {
        var str = cookie.substring(first, cookie.length);
        var last = str.indexOf(";");

        if (last < 0)
        {
            last = str.length;
        }

        str = str.substring(0, last).split("=");

        return unescape(str[1]);
    }
    else
    {
        return "";
    }        
}

function eraseCookie(key)
{
    var cookieDate = new Date(2000, 11, 10, 19, 30, 30);
    document.cookie = key + "=; expires=" + cookieDate.toGMTString() + "; path=/";
}