The answer is no secret, you always have to encode your parameters according to the char set your working on. In Javascript byte encoding is is a pain when you are trying to enconde every character but luckly server side encoding is really easy in PHP you can use mb_convert_encoding wich is a powerful function that works like a charm, there’s also the mb_detect_encoding wich will return the current encoding. In rails you can use iconv or add a library wich will make things easier.

In the end don’t get angry if your accented characters don’t parse correctly by your Ajax request, instead look for a way to encode your strings of characters properly.