Helper functions for weeks in moment.js

moment-weeks.js

var moment = require('moment');


moment.fn.isISO = true;

moment.fn.dayISO = function () {
    var self = this.clone();
    return self.day() == 0 ? 6 : self.day()-1;
}

moment.fn.weekISO = function () {
    var self = this.clone();
    return self.day() == 0 ? self.format('w')-1 : self.format('w');
}

moment.fn.week = function () {
    var self = this.clone(),
        day = self.isISO ? self.dayISO() : self.day();
    return {
        begin: self.subtract('days', day).clone(),
        end:   self.add('days', 6).clone()
    }
}

moment.fn.monthWeeks = function () {
    var self = this.clone(),
        first = self.startOf('month');
    first = self.isISO ? self.dayISO() : self.day();
    
    var day = 7-first,
        last = self.daysInMonth(),
        count = (last-day)/7;

    var weeks = [];
    weeks.push({
        begin: 1,
        end: day
    });
    for (var i=0; i < count; i++) {
        weeks.push({
            begin: day+1,
            end: Math.min(day+=7, last),
        });
    }
    return weeks;
}

moment.fn.weeksTo = function (target) {
    var self = this.clone(),
        end = target.clone();
    var day, from, to;
    day  = self.isISO ? self.dayISO() : self.day();
    from = self.subtract('days', day);
    day  = end.isISO ? end.dayISO() : end.day();
    to   = end.subtract('days', day);

    var result = [];
    result.push(from.format('w'));
    while (from.diff(to, 'weeks')) {
        result.push(from.add('weeks', 1).format('w'));
    }
    return result;
}