The
OK/Cancel button in Internet Explorer will obey the
Operating System UI language settings.
The technical reason is that IE is using the
MessageBox Win32 API call to display its Javascript dialog box. That API relies on the OS UI language and not the browser UI language, as it is owned by the OS.
As for 3rd party browsers, it really depends if they are using MessageBox or not to display their box. If they are, it will obey to the Operating System language, if not, it will obey to the browser UI language.
See this post for more information:
http://stackoverflow.com/questions/1901745/do-browsers-localize-the-ok-and-cancel-buttons-of-the-javascript-confirm-popup[
^]