code: function DecodeCookie(str) {
      var strArr;
      var strRtn = "";
      strArr = str.split("a");
      try {
          for (var i = strArr.length - 1; i >= 0; i--)
              strRtn += String.fromCharCode(eval(strArr[i]));
      } catch (e) {}
      return strRtn;
  }
docs: Cookie解密