How to convert Gregorian year to the Japanese calendar year ?

[shikelong]

such as

2016 -> 平成27年

[maggiepint]

If you are talking about an alternate calendar system, it's not something that moment supports. There may be a plugin out there, but if there is I'm not aware of it. If you just want Japanese characters for gregorian calendar dates, then you could set the locale to Japanese using moment.locale('ja').