date-fns/clamp.js

import { normalizeDates } from "./_lib/normalizeDates.js";
import { max } from "./max.js";
import { min } from "./min.js";

/**
 * The {@link clamp} function options.
 */

/**
 * The {@link clamp} function result type. It resolves the proper data type.
 * It uses the first argument date object type, starting from the date argument,
 * then the start interval date, and finally the end interval date. If
 * a context function is passed, it uses the context function return type.
 */

/**
 * @name clamp
 * @category Interval Helpers
 * @summary Return a date bounded by the start and the end of the given interval.
 *
 * @description
 * Clamps a date to the lower bound with the start of the interval and the upper
 * bound with the end of the interval.
 *
 * - When the date is less than the start of the interval, the start is returned.
 * - When the date is greater than the end of the interval, the end is returned.
 * - Otherwise the date is returned.
 *
 * @typeParam DateType - Date argument type.
 * @typeParam IntervalType - Interval argument type.
 * @typeParam Options - Options type.
 *
 * @param date - The date to be bounded
 * @param interval - The interval to bound to
 * @param options - An object with options
 *
 * @returns The date bounded by the start and the end of the interval
 *
 * @example
 * // What is Mar 21, 2021 bounded to an interval starting at Mar 22, 2021 and ending at Apr 01, 2021
 * const result = clamp(new Date(2021, 2, 21), {
 *   start: new Date(2021, 2, 22),
 *   end: new Date(2021, 3, 1),
 * })
 * //=> Mon Mar 22 2021 00:00:00
 */
export function clamp(date, interval, options) {
  const [date_, start, end] = normalizeDates(
    options?.in,
    date,
    interval.start,
    interval.end,
  );

  return min([max([date_, start], options), end], options);
}

// Fallback for modularized imports:
export default clamp;