/**
 * Created by beenotung on 2017 Mar 9th.
 */
export declare function setLang(lang: 'en' | 'en-US' | 'en-GK' | 'zh' | 'zh-HK' | 'zh-TW', flag?: 'simple'): void;
export declare function format_byte(n_byte: number, n_decimal?: number): string;
export type FormatDateTimeOptions = {
    locales?: string;
    empty?: string;
    timezoneOffset?: number;
} & Intl.DateTimeFormatOptions;
export declare function format_datetime(time: number, options?: FormatDateTimeOptions): string;
export declare function round_time_diff(timeDiff: number): number;
export declare function format_long_short_time(time: number, options?: {
    threshold?: number;
    format_duration_digit?: number;
} & FormatDateTimeOptions): string;
export declare function format_time_duration(delta: number, digit?: number): string;
export declare function format_relative_time(delta: number, digit?: number): string;
/**
 * mainly for formatting month, date, hour, minute, and second
 * @param x: [0..60]
 * */
export declare function format_2_digit(x: number): string;
/**
 * format: YYYYMMDD-HHMM
 * less accurate, for human reading
 * */
export declare function format_time_code(time: number, separator?: string): string;
/**
 * format: YYYYMMDD-HHMM-SS-sss
 * more accurate, for filename
 * */
export declare function format_timestamp_code(time: number, separator?: string): string;
export declare function format_n_digit(x: number, n: number, prefix?: string): string;
export declare function format_percentage(p: number, n_decimal?: number): string;