calendar-month/month.js

vanillajs month data handler

function getDate(year, month, day) {
  return new Date(Date.UTC(year, month, day));
}

function addPreviousDays (list, i, n, month, year) {
  for(; i <= n ; i++ ) list.push({
    date: i,
    month: month,
    year: year,
    previous: true
  });
}

function addNextDays (list, i, n, month, year) {
  for(; i <= n ; i++ ) list.push({
    date: i,
    month: month,
    year: year,
    next: true
  });
}

function monthInformation(year, month, m, start_day){

  m = m || {};

  var i, n,
      d = getDate(year, month, 1),
      previous_month_d = getDate(year, month, 0),
      month_last_day = getDate(year, month + 1, 0),
      next_month_d = getDate(year, month + 1, 1);

  start_day = start_day || 0;
  m.start_day = start_day;

  var last_day = previous_month_d.getUTCDate();
  var last_week_day = previous_month_d.getUTCDay();

  m.meta = {
    date: d,
    last_day: last_day,
    last_week_day: last_week_day,
    week_day: d.getUTCDay(),
    month_last_day: month_last_day
  };

  m.year = d.getUTCFullYear();
  m.month = d.getUTCMonth();

  var list = [], lastMonthFirstWeekDay = last_day - last_week_day + start_day;

  // previous month days
  addPreviousDays(
    list,
    lastMonthFirstWeekDay,
    last_week_day - start_day + lastMonthFirstWeekDay,
    previous_month_d.getUTCMonth(),
    previous_month_d.getUTCFullYear()
  );

  // current month days
  for( i = 1, n = month_last_day.getUTCDate() ; i <= n ; i++ ) list.push({
    date: i,
    month: month,
    year: year,
    current: true
  });

  // next month days
  addNextDays(
    list,
    1,
    42 - list.length,
    next_month_d.getUTCMonth(),
    next_month_d.getUTCFullYear()
  );

  m.days = list;

  return m;
}

var default_start_day = 0;

function Month (year, month, start_day) {
  if( month < 0 ) {
    month += 12;
    year -= 1;
  } else if( month > 11 ) {
    month -= 12;
    year += 1;
  }

  if( year instanceof Date ) {
    month = year.getUTCMonth();
    year = year.getUTCFullYear();
  }

  monthInformation(year, month, this, start_day || default_start_day);
}

Month.options = {};
Month.setFirstWeekDay = function (start_day) {
  default_start_day = start_day;
};

Month.prototype.previous = function () {
  return new Month(this.year, this.month - 1, this.start_day);
};

Month.prototype.next = function () {
  return new Month(this.year, this.month + 1, this.start_day);
};

Month.prototype.getColumns = function() {
  var columns = [], column;

  for( var c = 0; c < 7; c++ ) {
    column = [];
    columns.push(column);
    for( var r = 0; r < 6; r++ ) {
      column.push( this.days[ r*7 + c ] );
    }
  }

  return columns;
};

module.exports = Month;