AJAX utf-8 encoding problem

[danielle]

The following code using AJAX POST causes some Chinese characters to turn into question marks. The same string submitted in a regular form with accept-charset=utf-8 works without any problem.

I googled around and couldn't find a solution. Any suggestion on how to tackle this problem would be greatly appreciated.

xmlHttp.open('POST', url, true);
xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlHttp.setRequestHeader("Content-length", postString.length);
xmlHttp.setRequestHeader("Accept-Charset","UTF-8");
xmlHttp.setRequestHeader("Connection", "close");

xmlHttp.send(postString);