/**
 * Gets the current age in years based on the specified starting date and today's date.
 * @param {Date} startingDate - The starting date.
 * @return {number} A numeric value representing the age in years.
 */
export declare function toCurrentAge(startingDate: Date): number;
/**
 * Gets the day suffix for the specified date, i.e. st, nd, rd, or th.
 * @param {Date} date - The date to get a day suffix for.
 * @return {string} The day suffix as a string.
 */
export declare function toDaySuffix(date: Date): string;
/**
 * Rounds the date value to its nearest hour determined by the half hour of each hour.
 * @param {Date} date - The date to round to the nearest hour.
 * @return {Date} The date rounded to the nearest whole hour.
 */
export declare function toNearestHour(date: Date): Date;
/**
 * Gets the start of the day represented by the specified date.
 * @param {Date} date - The date.
 * @return {Date} A new date with the same date with the time set to midnight.
 */
export declare function startOfDay(date: Date): Date;
/**
 * Gets the end of the day represented by the specified date.
 * @param {Date} date - The date.
 * @return {Date} A new date with the same date with the time set to just before midnight of the next day.
 */
export declare function endOfDay(date: Date): Date;
/**
 * Sets the time value of a date.
 * @param {Date} date - The date value to set the time of.
 * @param {number} hours - The hours to set.
 * @param {number} minutes - The minutes to set.
 * @param {number} seconds - The seconds to set.
 * @param {number} milliseconds - The milliseconds to set.
 * @return {Date} A new date with the time set.
 */
export declare function setTime(date: Date, hours: number, minutes: number, seconds: number, milliseconds: number): Date;