I am having issue in displaying some Spanish characters through javascript. Below is an example of string.
Almería|Barcelona|Córdoba

When I use following command, it works fine

var result = "Almería|Barcelona|Córdoba";
alert(result);

But when string is parsed into xmlHttp.responseText it display invalid characters in between the string

var result = xmlHttp.responseText;
alert(result);

Check with firefox and something like "livehttpheaders" or "tamper data" what is the charset of the answer.
For accented characters like yours, it should be

Content-Type: text/html; charset=utf-8

If it's not utf-8, then the browser tries to convert it in another encoding, and it might be your problem.