/**
 * Pad the number of digits
 * @param digit number
 * @param len length
 */
export declare const fillDigit: (digit: number, len: number) => string;
/**
 * Check the device
 */
export declare const isPC: () => boolean;
/**
 * True on macOS / iOS (Command key). False on Windows, Linux, etc.
 */
export declare const isMac: () => boolean;
/**
 * Check the URL string
 */
export declare const isValidURL: (url: string) => boolean;
/**
 * Convert HTML to plain text.
 */
export declare const htmlToText: (html: string) => string;
/**
 * Compare floating-point numbers.
 */
export declare const isFloatEqual: (a: number, b: number, epsilon?: number) => boolean;
/**
 * Round a number to a fixed number of fraction digits.
 */
export declare const toFixed: (num: number, fractionDigits?: number) => number;