closestIndexTo.js 1.6 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657
  1. "use strict";
  2. exports.closestIndexTo = closestIndexTo;
  3. var _index = require("./toDate.js");
  4. /**
  5. * @name closestIndexTo
  6. * @category Common Helpers
  7. * @summary Return an index of the closest date from the array comparing to the given date.
  8. *
  9. * @description
  10. * Return an index of the closest date from the array comparing to the given date.
  11. *
  12. * @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).
  13. *
  14. * @param dateToCompare - The date to compare with
  15. * @param dates - The array to search
  16. *
  17. * @returns An index of the date closest to the given date or undefined if no valid value is given
  18. *
  19. * @example
  20. * // Which date is closer to 6 September 2015?
  21. * const dateToCompare = new Date(2015, 8, 6)
  22. * const datesArray = [
  23. * new Date(2015, 0, 1),
  24. * new Date(2016, 0, 1),
  25. * new Date(2017, 0, 1)
  26. * ]
  27. * const result = closestIndexTo(dateToCompare, datesArray)
  28. * //=> 1
  29. */
  30. function closestIndexTo(dateToCompare, dates) {
  31. const date = (0, _index.toDate)(dateToCompare);
  32. if (isNaN(Number(date))) return NaN;
  33. const timeToCompare = date.getTime();
  34. let result;
  35. let minDistance;
  36. dates.forEach(function (dirtyDate, index) {
  37. const currentDate = (0, _index.toDate)(dirtyDate);
  38. if (isNaN(Number(currentDate))) {
  39. result = NaN;
  40. minDistance = NaN;
  41. return;
  42. }
  43. const distance = Math.abs(timeToCompare - currentDate.getTime());
  44. if (result == null || distance < minDistance) {
  45. result = index;
  46. minDistance = distance;
  47. }
  48. });
  49. return result;
  50. }