// setCookie(クッキー名, 値, 有効期限日数)
function setCookie(key, value, day){
   var _time = new Date();
   _time.setTime(_time.getTime() + (day * 24 * 60 * 60 * 1000));
   var _item = "@" + key + "=" + escape(value) + ";";
   var _expires = "expires=" + _time.toGMTString();
   document.cookie =  _item + _expires + ";path=/";
};

// getCookie(クッキー名)
function getCookie(key){
   var _cookie = "@" + key + "=";
   var _str = document.cookie + ";" ;
   var _offset = _str.indexOf(_cookie);
   
   var _value = null;
   if (0 <= _offset) {
      var _start = _offset + _cookie.length;
      var _end = _str.indexOf(";" , _start);
      _value = unescape(_str.substring(_start, _end));
   }
   return _value;
};