Calculating time values and displaying them correctly is not child's play. There are lots of different units (Year, Month, Day, Hour etc.) and - more disturbing - different systems of numeration, none of which is decimal. But you need not fall into despair. Moment.js is there to help you. The small JavaScript library comes equipped with lots of nifty features for calculating time spans, converting international time formats and also cares for the output of the results. Needless to say that Moment.js works for different languages and time zones.