Well, everything is just bytes until the web browser interprets them and translates them into characters for presentation to the user. Therefore, it does not matter what happens in AJAX, as in any case there will be an encoding conflict.
, AJAX "å", UTF-8, 0xc3a5. , - , UTF-8, "å" , . , - , , Latin1, , 0xc3 0xa5, , , Ã ¥.