date-fns/compareAsc.js

import { toDate } from "./toDate.js";

/**
 * @name compareAsc
 * @category Common Helpers
 * @summary Compare the two dates and return -1, 0 or 1.
 *
 * @description
 * Compare the two dates and return 1 if the first date is after the second,
 * -1 if the first date is before the second or 0 if dates are equal.
 *
 * @param dateLeft - The first date to compare
 * @param dateRight - The second date to compare
 *
 * @returns The result of the comparison
 *
 * @example
 * // Compare 11 February 1987 and 10 July 1989:
 * const result = compareAsc(new Date(1987, 1, 11), new Date(1989, 6, 10))
 * //=> -1
 *
 * @example
 * // Sort the array of dates:
 * const result = [
 *   new Date(1995, 6, 2),
 *   new Date(1987, 1, 11),
 *   new Date(1989, 6, 10)
 * ].sort(compareAsc)
 * //=> [
 * //   Wed Feb 11 1987 00:00:00,
 * //   Mon Jul 10 1989 00:00:00,
 * //   Sun Jul 02 1995 00:00:00
 * // ]
 */
export function compareAsc(dateLeft, dateRight) {
  const diff = +toDate(dateLeft) - +toDate(dateRight);

  if (diff < 0) return -1;
  else if (diff > 0) return 1;

  // Return 0 if diff is 0; return NaN if diff is NaN
  return diff;
}

// Fallback for modularized imports:
export default compareAsc;