moment.duration().weeks(); moment.duration().asWeeks();

As with the other getters for durations, moment.duration().weeks() gets the weeks (0 - 4).

moment.duration().asWeeks() gets the length of the duration in weeks.

Pay attention that unlike the other getters for duration, weeks are counted as a subset of the days, and are not taken off the days count.

Note: The length of a duration in weeks is defined as 7 days.