@lou.codes/cron/dist/nextDates.js

⏲️ Cron Quartz and Cron UNIX expression parser

import { EMPTY_STRING } from "@lou.codes/constants/empty.js";
import { createIterableIterator } from "@lou.codes/iterables";
import { isString, isUndefined } from "@lou.codes/predicates";
import { DIGIT, build, escape, quantity } from "functional-expression";
import { dateInCron } from "./dateInCron.js";
import { parse } from "./parse.js";
import { stringify } from "./stringify.js";
/**
 * Get next ISO date iterator for the given date and the given cron expression.
 *
 * @category Util
 * @example
 * ```typescript
 * take(2)(nextDates(new Date("1989-10-13T10:15:00.000Z"))("* * * * *"));
 * // [Date("1989-10-13T10:16:00.000"), Date("1989-10-13T10:17:00.000Z")]
 * ```
 * @param date Base date to get the next date from.
 * @returns Curried function with date set.
 */
export const nextDates = date => cron =>
	createIterableIterator(function* () {
		const cronObject = parse(
			isString(cron) ? cron : (stringify(cron) ?? EMPTY_STRING),
		);
		// eslint-disable-next-line functional/no-conditional-statements
		if (!isUndefined(cronObject)) {
			const validDate = dateInCron(cronObject);
			const now = new Date(
				date
					.toISOString()
					.replace(
						build()(
							quantity(2)(DIGIT),
							escape("."),
							quantity(3)(DIGIT),
						),
						"00.000",
					),
			);
			// eslint-disable-next-line functional/no-loop-statements
			for (;;) {
				// eslint-disable-next-line @typescript-eslint/no-unused-expressions
				validDate((now.setMinutes(now.getMinutes() + 1), now)) ?
					yield new Date(now)
				:	undefined;
			}
		}
	});