import { DateInput, Unit } from './types';
/**
 * Checks if a date is before another date or a specified time unit.
 * 检查一个日期是否在另一个日期或指定的时间单位之前。
 *
 * @param date - The date to compare. (要比较的日期。)
 * @param input - The date or time unit to compare against. (要比较的日期或时间单位。)
 * @param unit - The unit of time to compare (e.g., 'year', 'month', 'day', 'hour', 'minute', 'second', 'millisecond').
 * (要比较的时间单位，例如 'year'、'month'、'day'、'hour'、'minute'、'second'、'millisecond'。)
 * @returns A boolean indicating whether the first date is before the second date or time unit.
 * (布尔值，表示第一个日期是否在第二个日期或时间单位之前。)
 * @example
 * ```ts
 * // Checking if a date is before another date (检查一个日期是否在另一个日期之前)
 * const date1 = new Date('2023-09-01');
 * const date2 = new Date('2023-10-01');
 * const isBeforeDate = isBefore(date1, date2, 'day');
 * console.log(isBeforeDate); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific year (检查一个日期是否在特定年份之前)
 * const date3 = new Date('2022-12-31');
 * const isBeforeYear = isBefore(date3, 2023, 'year');
 * console.log(isBeforeYear); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific month (检查一个日期是否在特定月份之前)
 * const date4 = new Date('2023-09-01');
 * const isBeforeMonth = isBefore(date4, '2023-10', 'month');
 * console.log(isBeforeMonth); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific day (检查一个日期是否在特定天数之前)
 * const date5 = new Date('2023-10-01');
 * const isBeforeDay = isBefore(date5, '2023-10-02', 'day');
 * console.log(isBeforeDay); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific hour (检查一个日期是否在特定小时之前)
 * const date6 = new Date('2023-10-01T12:00:00');
 * const isBeforeHour = isBefore(date6, '2023-10-01T13:00:00', 'hour');
 * console.log(isBeforeHour); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific minute (检查一个日期是否在特定分钟之前)
 * const date7 = new Date('2023-10-01T12:00:00');
 * const isBeforeMinute = isBefore(date7, '2023-10-01T12:01:00', 'minute');
 * console.log(isBeforeMinute); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific second (检查一个日期是否在特定秒数之前)
 * const date8 = new Date('2023-10-01T12:00:00');
 * const isBeforeSecond = isBefore(date8, '2023-10-01T12:00:01', 'second');
 * console.log(isBeforeSecond); // Outputs: true (输出: true)
 *
 * // Checking if a date is before a specific millisecond (检查一个日期是否在特定毫秒数之前)
 * const date9 = new Date('2023-10-01T12:00:00.000');
 * const isBeforeMillisecond = isBefore(date9, '2023-10-01T12:00:00.500', 'millisecond');
 * console.log(isBeforeMillisecond); // Outputs: true (输出: true)
 * ```
 */
export default function isBefore(date: Date, input: DateInput, unit?: Unit): boolean;