/**
 * Retrieves the last date of the month for the given date.
 *
 * @example
 * lastDateOfMonth("2024-02-01") // 2024-02-29
 *
 * @param date The date to check. Defaults to the current date.
 * @returns A new Date object set to the last day of the month.
 */
export declare function lastDateOfMonth(date?: Date | string | number | null): Date;