// From version 2.8.1 onward moment.locale();

// Deprecated in version 2.8.1 moment.lang();

If you are changing locales frequently, you may want to know what locale is currently being used. This is as simple as calling moment.locale without any parameters.

moment.locale('en'); // set to english
moment.locale(); // returns 'en'
moment.locale('fr'); // set to french
moment.locale(); // returns 'fr'

As of version 2.12.0 it is possible to list all locales that have been loaded and are available to use: