[flexcoders] AS3 method exist returning the # of bytes a String is?

[e_baggg]

I am implementing a spell checker and am hitting some issues because
for non-Ascii characters such as "ò"...this is actually two bytes
where a normal character is 1 byte...which throws off the start and
end index of the text in the textArea.

Do any Flash/AS3 methods exist that return the number of bytes a given
String is? Or do I need to create my own loop counting each character
and if the charCode is >= 128...then it is 2 bytes?

Thanks in advance.