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  1. import startOfWeek from '../startOfWeek/index.js';
  2. import toDate from '../toDate/index.js';
  3. import toInteger from '../_lib/toInteger/index.js';
  4. import requiredArgs from '../_lib/requiredArgs/index.js';
  5. /**
  6. * @name getWeekYear
  7. * @category Week-Numbering Year Helpers
  8. * @summary Get the local week-numbering year of the given date.
  9. *
  10. * @description
  11. * Get the local week-numbering year of the given date.
  12. * The exact calculation depends on the values of
  13. * `options.weekStartsOn` (which is the index of the first day of the week)
  14. * and `options.firstWeekContainsDate` (which is the day of January, which is always in
  15. * the first week of the week-numbering year)
  16. *
  17. * Week numbering: https://en.wikipedia.org/wiki/Week#Week_numbering
  18. *
  19. * ### v2.0.0 breaking changes:
  20. *
  21. * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
  22. *
  23. * @param {Date|Number} date - the given date
  24. * @param {Object} [options] - an object with options.
  25. * @param {Locale} [options.locale=defaultLocale] - the locale object. See [Locale]{@link https://date-fns.org/docs/Locale}
  26. * @param {0|1|2|3|4|5|6} [options.weekStartsOn=0] - the index of the first day of the week (0 - Sunday)
  27. * @param {1|2|3|4|5|6|7} [options.firstWeekContainsDate=1] - the day of January, which is always in the first week of the year
  28. * @returns {Number} the local week-numbering year
  29. * @throws {TypeError} 1 argument required
  30. * @throws {RangeError} `options.weekStartsOn` must be between 0 and 6
  31. * @throws {RangeError} `options.firstWeekContainsDate` must be between 1 and 7
  32. *
  33. * @example
  34. * // Which week numbering year is 26 December 2004 with the default settings?
  35. * var result = getWeekYear(new Date(2004, 11, 26))
  36. * //=> 2005
  37. *
  38. * @example
  39. * // Which week numbering year is 26 December 2004 if week starts on Saturday?
  40. * var result = getWeekYear(new Date(2004, 11, 26), { weekStartsOn: 6 })
  41. * //=> 2004
  42. *
  43. * @example
  44. * // Which week numbering year is 26 December 2004 if the first week contains 4 January?
  45. * var result = getWeekYear(new Date(2004, 11, 26), { firstWeekContainsDate: 4 })
  46. * //=> 2004
  47. */
  48. export default function getWeekYear(dirtyDate, dirtyOptions) {
  49. requiredArgs(1, arguments);
  50. var date = toDate(dirtyDate);
  51. var year = date.getFullYear();
  52. var options = dirtyOptions || {};
  53. var locale = options.locale;
  54. var localeFirstWeekContainsDate = locale && locale.options && locale.options.firstWeekContainsDate;
  55. var defaultFirstWeekContainsDate = localeFirstWeekContainsDate == null ? 1 : toInteger(localeFirstWeekContainsDate);
  56. var firstWeekContainsDate = options.firstWeekContainsDate == null ? defaultFirstWeekContainsDate : toInteger(options.firstWeekContainsDate); // Test if weekStartsOn is between 1 and 7 _and_ is not NaN
  57. if (!(firstWeekContainsDate >= 1 && firstWeekContainsDate <= 7)) {
  58. throw new RangeError('firstWeekContainsDate must be between 1 and 7 inclusively');
  59. }
  60. var firstWeekOfNextYear = new Date(0);
  61. firstWeekOfNextYear.setFullYear(year + 1, 0, firstWeekContainsDate);
  62. firstWeekOfNextYear.setHours(0, 0, 0, 0);
  63. var startOfNextYear = startOfWeek(firstWeekOfNextYear, dirtyOptions);
  64. var firstWeekOfThisYear = new Date(0);
  65. firstWeekOfThisYear.setFullYear(year, 0, firstWeekContainsDate);
  66. firstWeekOfThisYear.setHours(0, 0, 0, 0);
  67. var startOfThisYear = startOfWeek(firstWeekOfThisYear, dirtyOptions);
  68. if (date.getTime() >= startOfNextYear.getTime()) {
  69. return year + 1;
  70. } else if (date.getTime() >= startOfThisYear.getTime()) {
  71. return year;
  72. } else {
  73. return year - 1;
  74. }
  75. }