/**
 * Extract the uppercase extension of a file name, without the leading dot.
 * @param fileName The name of the file.
 * @returns The uppercase extension, or an empty string when the file has none.
 * @example
 * getFileExtension('report.final.pdf') // returns 'PDF'
 * getFileExtension('archive') // returns ''
 * getFileExtension('.gitignore') // returns ''
 */
export declare function getFileExtension(fileName: string): string;
/**
 * Format a size in bytes into a human readable string, using a 1024 base.
 * @param bytes The size in bytes.
 * @param decimals The number of decimal places to round to (default is 2).
 * @returns The formatted size, suffixed with its unit.
 * @example
 * formatFileSize(0) // returns '0 B'
 * formatFileSize(820) // returns '820 B'
 * formatFileSize(5123456) // returns '4.89 MB'
 * formatFileSize(5123456, 1) // returns '4.9 MB'
 */
export declare function formatFileSize(bytes: number, decimals?: number): string;