function addCookie(cookieName, value, days) {
    if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
        var expires = "; expires=" + date.toGMTString();
    }
    else var expires = "";
    document.cookie = cookieName + "=" + value + expires + "; path=/";
}

function checkCookie(cookieName) {
    var name = cookieName + "=";
    var ca = document.cookie.split(';');
    for (var i = 0; i < ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') c = c.substring(1, c.length);
        if (c.indexOf(name) == 0) return c.substring(name.length, c.length);
    }
    return null;
}

function deleteCookie(name) {
    addCookie(name, "", -1);
}