differenceInCalendarWeeks.js 1.8 KB

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  1. import { getTimezoneOffsetInMilliseconds } from "./_lib/getTimezoneOffsetInMilliseconds.js";
  2. import { normalizeDates } from "./_lib/normalizeDates.js";
  3. import { millisecondsInWeek } from "./constants.js";
  4. import { startOfWeek } from "./startOfWeek.js";
  5. /**
  6. * The {@link differenceInCalendarWeeks} function options.
  7. */
  8. /**
  9. * @name differenceInCalendarWeeks
  10. * @category Week Helpers
  11. * @summary Get the number of calendar weeks between the given dates.
  12. *
  13. * @description
  14. * Get the number of calendar weeks between the given dates.
  15. *
  16. * @param laterDate - The later date
  17. * @param earlierDate - The earlier date
  18. * @param options - An object with options.
  19. *
  20. * @returns The number of calendar weeks
  21. *
  22. * @example
  23. * // How many calendar weeks are between 5 July 2014 and 20 July 2014?
  24. * const result = differenceInCalendarWeeks(
  25. * new Date(2014, 6, 20),
  26. * new Date(2014, 6, 5)
  27. * )
  28. * //=> 3
  29. *
  30. * @example
  31. * // If the week starts on Monday,
  32. * // how many calendar weeks are between 5 July 2014 and 20 July 2014?
  33. * const result = differenceInCalendarWeeks(
  34. * new Date(2014, 6, 20),
  35. * new Date(2014, 6, 5),
  36. * { weekStartsOn: 1 }
  37. * )
  38. * //=> 2
  39. */
  40. export function differenceInCalendarWeeks(laterDate, earlierDate, options) {
  41. const [laterDate_, earlierDate_] = normalizeDates(
  42. options?.in,
  43. laterDate,
  44. earlierDate,
  45. );
  46. const laterStartOfWeek = startOfWeek(laterDate_, options);
  47. const earlierStartOfWeek = startOfWeek(earlierDate_, options);
  48. const laterTimestamp =
  49. +laterStartOfWeek - getTimezoneOffsetInMilliseconds(laterStartOfWeek);
  50. const earlierTimestamp =
  51. +earlierStartOfWeek - getTimezoneOffsetInMilliseconds(earlierStartOfWeek);
  52. return Math.round((laterTimestamp - earlierTimestamp) / millisecondsInWeek);
  53. }
  54. // Fallback for modularized imports:
  55. export default differenceInCalendarWeeks;