As of version 2.2, MathJax's user interface (including its contextual menu, its help and about dialog boxes, and its warning messages) can all be localized to appear in languages other than English. For the available language options, see the TranslateWiki.net interface.
The language used by MathJax can be selected using the MathJax contextual menu. It includes a Language submenu that lists the available languages; selecting one will change the MathJax user interface to use that language.
Page authors can select a default language for MathJax so that, for
example, a page that is written in French will have MathJax's user
interface also in French. To do this, add &locale=XX after the
configuration file in the <script> tag that loads the MathJax.js
file, where XX is the two-letter code for the language. For
example:
<script src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS_HTML&locale=fr"></script>will load MathJax using the French language. Users can still override this setting using the Language submenu of the MathJax contextual menu. This submenu can be disabled, however, using the :ref:`MathMenu configuration options <configure-MathMenu>`.
If you want to help in the translation process, please visit the TranslateWiki.net interface. The page localization.html is a convenient way to check the different translations.