index.js 2.82 KB
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = getWeekOfMonth;

var _index = _interopRequireDefault(require("../getDate/index.js"));

var _index2 = _interopRequireDefault(require("../getDay/index.js"));

var _index3 = _interopRequireDefault(require("../startOfMonth/index.js"));

var _index4 = _interopRequireDefault(require("../_lib/toInteger/index.js"));

var _index5 = _interopRequireDefault(require("../_lib/requiredArgs/index.js"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * @name getWeekOfMonth
 * @category Week Helpers
 * @summary Get the week of the month of the given date.
 *
 * @description
 * Get the week of the month of the given date.
 *
 * ### v2.0.0 breaking changes:
 *
 * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
 *
 * @param {Date|Number} date - the given date
 * @param {Object} [options] - an object with options.
 * @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
 * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
 * @returns {Number} the week of month
 * @throws {TypeError} 1 argument required
 * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
 *
 * @example
 * // Which week of the month is 9 November 2017?
 * var result = getWeekOfMonth(new Date(2017, 10, 9))
 * //=> 2
 */
function getWeekOfMonth(date, dirtyOptions) {
  (0, _index5.default)(1, arguments);
  var options = dirtyOptions || {};
  var locale = options.locale;
  var localeWeekStartsOn = locale && locale.options && locale.options.weekStartsOn;
  var defaultWeekStartsOn = localeWeekStartsOn == null ? 0 : (0, _index4.default)(localeWeekStartsOn);
  var weekStartsOn = options.weekStartsOn == null ? defaultWeekStartsOn : (0, _index4.default)(options.weekStartsOn); // Test if weekStartsOn is between 0 and 6 _and_ is not NaN

  if (!(weekStartsOn >= 0 && weekStartsOn <= 6)) {
    throw new RangeError('weekStartsOn must be between 0 and 6 inclusively');
  }

  var currentDayOfMonth = (0, _index.default)(date);

  if (isNaN(currentDayOfMonth)) {
    return currentDayOfMonth;
  }

  var startWeekDay = (0, _index2.default)((0, _index3.default)(date));
  var lastDayOfFirstWeek = 0;

  if (startWeekDay >= weekStartsOn) {
    lastDayOfFirstWeek = weekStartsOn + 7 - startWeekDay;
  } else {
    lastDayOfFirstWeek = weekStartsOn - startWeekDay;
  }

  var weekNumber = 1;

  if (currentDayOfMonth > lastDayOfFirstWeek) {
    var remainingDaysAfterFirstWeek = currentDayOfMonth - lastDayOfFirstWeek;
    weekNumber = weekNumber + Math.ceil(remainingDaysAfterFirstWeek / 7);
  }

  return weekNumber;
}

module.exports = exports.default;