getWeekYear.js 2.8 KB

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  1. "use strict";
  2. exports.getWeekYear = getWeekYear;
  3. var _index = require("./constructFrom.js");
  4. var _index2 = require("./startOfWeek.js");
  5. var _index3 = require("./toDate.js");
  6. var _index4 = require("./_lib/defaultOptions.js");
  7. /**
  8. * The {@link getWeekYear} function options.
  9. */
  10. /**
  11. * @name getWeekYear
  12. * @category Week-Numbering Year Helpers
  13. * @summary Get the local week-numbering year of the given date.
  14. *
  15. * @description
  16. * Get the local week-numbering year of the given date.
  17. * The exact calculation depends on the values of
  18. * `options.weekStartsOn` (which is the index of the first day of the week)
  19. * and `options.firstWeekContainsDate` (which is the day of January, which is always in
  20. * the first week of the week-numbering year)
  21. *
  22. * Week numbering: https://en.wikipedia.org/wiki/Week#The_ISO_week_date_system
  23. *
  24. * @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
  25. *
  26. * @param date - The given date
  27. * @param options - An object with options.
  28. *
  29. * @returns The local week-numbering year
  30. *
  31. * @example
  32. * // Which week numbering year is 26 December 2004 with the default settings?
  33. * const result = getWeekYear(new Date(2004, 11, 26))
  34. * //=> 2005
  35. *
  36. * @example
  37. * // Which week numbering year is 26 December 2004 if week starts on Saturday?
  38. * const result = getWeekYear(new Date(2004, 11, 26), { weekStartsOn: 6 })
  39. * //=> 2004
  40. *
  41. * @example
  42. * // Which week numbering year is 26 December 2004 if the first week contains 4 January?
  43. * const result = getWeekYear(new Date(2004, 11, 26), { firstWeekContainsDate: 4 })
  44. * //=> 2004
  45. */
  46. function getWeekYear(date, options) {
  47. const _date = (0, _index3.toDate)(date);
  48. const year = _date.getFullYear();
  49. const defaultOptions = (0, _index4.getDefaultOptions)();
  50. const firstWeekContainsDate =
  51. options?.firstWeekContainsDate ??
  52. options?.locale?.options?.firstWeekContainsDate ??
  53. defaultOptions.firstWeekContainsDate ??
  54. defaultOptions.locale?.options?.firstWeekContainsDate ??
  55. 1;
  56. const firstWeekOfNextYear = (0, _index.constructFrom)(date, 0);
  57. firstWeekOfNextYear.setFullYear(year + 1, 0, firstWeekContainsDate);
  58. firstWeekOfNextYear.setHours(0, 0, 0, 0);
  59. const startOfNextYear = (0, _index2.startOfWeek)(
  60. firstWeekOfNextYear,
  61. options,
  62. );
  63. const firstWeekOfThisYear = (0, _index.constructFrom)(date, 0);
  64. firstWeekOfThisYear.setFullYear(year, 0, firstWeekContainsDate);
  65. firstWeekOfThisYear.setHours(0, 0, 0, 0);
  66. const startOfThisYear = (0, _index2.startOfWeek)(
  67. firstWeekOfThisYear,
  68. options,
  69. );
  70. if (_date.getTime() >= startOfNextYear.getTime()) {
  71. return year + 1;
  72. } else if (_date.getTime() >= startOfThisYear.getTime()) {
  73. return year;
  74. } else {
  75. return year - 1;
  76. }
  77. }