import { DateInput, Unit } from './types';
/**
 * Calculates the difference between two dates in specified time units.
 * 计算两个日期之间的指定时间单位差异。
 *
 * @param date - The first date. (第一个日期。)
 * @param input - The second date. (第二个日期。)
 * @param unit - The unit of time to calculate the difference in
 * (e.g., 'year', 'month', 'day', 'hour', 'minute', 'second', 'millisecond').
 * (要计算差异的时间单位，例如 'year'、'month'、'day'、'hour'、'minute'、'second'、'millisecond'。)
 * @param asFloat - Whether to return the difference as a floating-point number. (是否以浮点数形式返回差异。)
 * @returns The difference between the two dates in the specified time units. (两个日期之间的指定时间单位差异。)
 * @example
 * ```ts
 * // Calculating the difference in years (计算年份差异)
 * const date1 = new Date('2023-01-01');
 * const date2 = new Date('2024-01-01');
 * const yearsDiff = diff(date1, date2, 'year');
 * console.log(yearsDiff); // Outputs: 1 (输出: 1)
 *
 * // Calculating the difference in months (计算月份差异)
 * const monthsDiff = diff(date1, date2, 'month');
 * console.log(monthsDiff); // Outputs: 12 (输出: 12)
 *
 * // Calculating the difference in days (计算天数差异)
 * const daysDiff = diff(date1, date2, 'day');
 * console.log(daysDiff); // Outputs: 365 (输出: 365)
 *
 * // Calculating the difference in hours (计算小时差异)
 * const hoursDiff = diff(date1, date2, 'hour');
 * console.log(hoursDiff); // Outputs: 8760 (输出: 8760)
 *
 * // Calculating the difference in minutes (计算分钟差异)
 * const minutesDiff = diff(date1, date2, 'minute');
 * console.log(minutesDiff); // Outputs: 525600 (输出: 525600)
 *
 * // Calculating the difference in seconds (计算秒数差异)
 * const secondsDiff = diff(date1, date2, 'second');
 * console.log(secondsDiff); // Outputs: 31536000 (输出: 31536000)
 *
 * // Calculating the difference in milliseconds (计算毫秒差异)
 * const msDiff = diff(date1, date2, 'millisecond');
 * console.log(msDiff); // Outputs: 31536000000 (输出: 31536000000)
 * ```
 */
export default function diff(date: Date, input: DateInput, unit: Unit, asFloat?: boolean): number;