We use the excellent validator plugin for jQuery here on Stack Overflow to do client-side validation of input before it is submitted to the server.
It generally work
This isn't really an answer but I don't have 50 rep yet to add a comment... It can definately be attributed to encoding issues.
Yea "ECMA shouldn't care about encoding..." blah blah, well if you're on firefox, go to View > Character Encoding > Western (ISO-8859-1) then try using the Name field.
It works fine for me after changing the encoding manually (granted the rest of the page doesn't like the encoding switch, :P)
(on IE8 you can go to Page > Encoding > Western European (Windows) to get the same effect)