Formats a filesize into a human readable format. First parameter is filesize in bytes, second parameter is the precision of the resulting float and the last parameter is the system (choose between 'decimal' aka SI-based or 'binary' based calculation).

formatFilesize.ts

enum FileSizeSystems {
	Decimal = 'decimal',
	Binary = 'binary',
}
const formatFilesize = (size: number, decimals: number = 1, system: FileSizeSystems = FileSizeSystems.Decimal): string => {
	const fileSizes = {
		[FileSizeSystems.Decimal]: ['Byte', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
		[FileSizeSystems.Binary]: ['Byte', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB'],
	}
	const base = {
		[FileSizeSystems.Decimal]: 1000,
		[FileSizeSystems.Binary]: 1024,
	}
	const steps = size > 0 ? Math.floor(Math.log(size) / Math.log(base[system])) : 0
	return parseFloat((size / Math.pow(base[system], steps)).toFixed(decimals)) + ' ' + fileSizes[system][steps]
}