Calendar Format2.14.0+

moment.calendarFormat = Function

This lets you modify the tokens used by calendar.

moment.calendarFormat = function (myMoment, now) {
    var diff = myMoment.diff(now, 'days', true);
    var nextMonth = now.clone().add(1, 'month');
    var retVal =  diff < -6 ? 'sameElse' :
        diff < -1 ? 'lastWeek' :
        diff < 0 ? 'lastDay' :
        diff < 1 ? 'sameDay' :
        diff < 2 ? 'nextDay' :
        diff < 7 ? 'nextWeek' :
        // introduce thisMonth and nextMonth
        (myMoment.month() === now.month() && myMoment.year() === now.year()) ? 'thisMonth' :
        (nextMonth.month() === myMoment.month() && nextMonth.year() === myMoment.year()) ? 'nextMonth' : 'sameElse';
    return retVal;
};