Generate matrix for calendar

getCalendarMatrix.js

/** 
 * Dependencies
 * moment
 * ramda
*/

/**
 *
 * @param {string} date
 * @param {Object} options 
 * @param {string} options.activeDay 
 * @returns {Array[]} matrix
 */
function getCalendarMatrix(dateString, options = {}) {
  const date = moment(dateString);
  const CURRENT_MONTH = date.month();
  const TODAY = moment().format('YYYY-MM-DD');

  // reset date
  date.date(1).isoWeekday(1).subtract(1, 'day');

  return R.range(0, 6).reduce(calendar => {
    const weeksOfMonth = R.range(0, 7).map(() => {
      date.add(1, 'day');

      return {
        isCurrentMonth: date.month() === CURRENT_MONTH,
        isToday: date.isSame(TODAY),
        isActive: date.isSame(options.activeDay),
        label: date.format('DD'),
        date: date.toString(),
      };
    });

    return R.append(weeksOfMonth, calendar);
  }, []);
}

/**
 * Example
 * getCalendarMatrix('2018-02-15')
 *
 * 29 30 31 01 02 03 04
 * 05 06 07 08 09 10 11
 * 12 13 14 15 16 17 18
 * 19 20 21 22 23 24 25
 * 26 27 28 01 02 03 04
 * 05 06 07 08 09 10 11
 */