pretty-bytes/index.d.ts

Convert bytes to a human readable string: 1337 → 1.34 kB

export type Options = {
	/**
	Include plus sign for positive numbers. If the difference is exactly zero a space character will be prepended instead for better alignment.

	@default false
	*/
	readonly signed?: boolean;

	/**
	- If `false`: Output won't be localized.
	- If `true`: Localize the output using the system/browser locale.
	- If `string`: Expects a [BCP 47 language tag](https://en.wikipedia.org/wiki/IETF_language_tag) (For example: `en`, `de`, …)
	- If `string[]`: Expects a list of [BCP 47 language tags](https://en.wikipedia.org/wiki/IETF_language_tag) (For example: `en`, `de`, …)

	Only the number and decimal separator are localized. The unit title is not and will not be localized.

	Note: A value below `1e-100` bytes needs more than the 100 fraction digits `Intl.NumberFormat` accepts, so it is written out with plain digits instead of a localized decimal separator.

	@default false

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1337, {locale: 'de'});
	//=> '1,34 kB'
	```
	*/
	readonly locale?: boolean | string | readonly string[];

	/**
	Format the number as [bits](https://en.wikipedia.org/wiki/Bit) instead of [bytes](https://en.wikipedia.org/wiki/Byte). This can be useful when, for example, referring to [bit rate](https://en.wikipedia.org/wiki/Bit_rate).

	@default false

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1337, {bits: true});
	//=> '1.34 kbit'
	```
	*/
	readonly bits?: boolean;

	/**
	Format the number using the [Binary Prefix](https://en.wikipedia.org/wiki/Binary_prefix) instead of the [SI Prefix](https://en.wikipedia.org/wiki/SI_prefix). This can be useful for presenting memory amounts. However, this should not be used for presenting file sizes.

	@default false

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1000, {binary: true});
	//=> '1000 B'

	prettyBytes(1024, {binary: true});
	//=> '1 KiB'
	```
	*/
	readonly binary?: boolean;

	/**
	The minimum number of fraction digits to display.

	@default undefined

	If neither `minimumFractionDigits` nor `maximumFractionDigits` is set, the default behavior is to round to 3 significant digits.

	Must be an integer between 0 and 100. Throws a `TypeError` for invalid values.

	Must not be greater than `maximumFractionDigits`, which throws a `RangeError` when both are set.

	Note: When `minimumFractionDigits` or `maximumFractionDigits` is specified, values are truncated instead of rounded to provide more intuitive results for file sizes.

	@example
	```
	import prettyBytes from 'pretty-bytes';

	// Show the number with at least 3 fractional digits
	prettyBytes(1900, {minimumFractionDigits: 3});
	//=> '1.900 kB'

	prettyBytes(1900);
	//=> '1.9 kB'
	```
	*/
	readonly minimumFractionDigits?: number;

	/**
	The maximum number of fraction digits to display.

	@default undefined

	If neither `minimumFractionDigits` nor `maximumFractionDigits` is set, the default behavior is to round to 3 significant digits.

	Must be an integer between 0 and 100. Throws a `TypeError` for invalid values.

	Must not be less than `minimumFractionDigits`, which throws a `RangeError` when both are set.

	Note: When `minimumFractionDigits` or `maximumFractionDigits` is specified, values are truncated instead of rounded to provide more intuitive results for file sizes.

	@example
	```
	import prettyBytes from 'pretty-bytes';

	// Show the number with at most 1 fractional digit
	prettyBytes(1920, {maximumFractionDigits: 1});
	//=> '1.9 kB'

	prettyBytes(1920);
	//=> '1.92 kB'
	```
	*/
	readonly maximumFractionDigits?: number;

	/**
	Put a space between the number and unit.

	@default true

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1920, {space: false});
	//=> '1.92kB'

	prettyBytes(1920);
	//=> '1.92 kB'
	```
	*/
	readonly space?: boolean;

	/**
	Use a non-breaking space instead of a regular space to prevent the unit from wrapping to a new line.

	Has no effect when `space` is `false`.

	@default false

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1337, {nonBreakingSpace: true});
	//=> '1.34\u00A0kB'

	prettyBytes(1337, {space: false, nonBreakingSpace: true});
	//=> '1.34kB'
	```
	*/
	readonly nonBreakingSpace?: boolean;

	/**
	Pad the output to a fixed width by right-aligning it.

	Useful for creating aligned columns in tables or progress bars.

	If the output is longer than the specified width, no padding is applied.

	Must be a non-negative integer. Throws a `TypeError` for invalid values.

	@default undefined

	@example
	```
	import prettyBytes from 'pretty-bytes';

	prettyBytes(1337, {fixedWidth: 10});
	//=> '   1.34 kB'

	prettyBytes(100_000, {fixedWidth: 10});
	//=> '    100 kB'

	// Useful for progress bars and tables
	[1000, 10_000, 100_000].map(bytes => prettyBytes(bytes, {fixedWidth: 8}));
	//=> ['    1 kB', '   10 kB', '  100 kB']
	```
	*/
	readonly fixedWidth?: number;
};

/**
Convert bytes to a human readable string: `1337` → `1.34 kB`.

@param number - The number to format.

A `bigint` of any size is accepted. Past roughly `1e332` bytes the scaled value no longer fits a `number`, and it is written out in full from the exact quotient, so it carries no grouping and no localized decimal separator, the same as a value below `1e-100`.

Byte counts are otherwise formatted with the precision of a JavaScript number, which holds about 16 significant digits, so above roughly `1e17` bytes the trailing digits of the output may not be exact. A value that rounds up onto a unit boundary can therefore be printed in the larger unit, so `999499999999999999` bytes is `1 EB` rather than `999 PB`.

Note: Rounding uses `Number#toPrecision`, so at an exact tie the direction comes from how that value is stored as a floating point number. `1005` bytes is `1.005 kB` and rounds down to `1 kB`, while `1125` bytes is `1.125 kB` and rounds up to `1.13 kB`.

@example
```
import prettyBytes from 'pretty-bytes';

prettyBytes(1337);
//=> '1.34 kB'

prettyBytes(100);
//=> '100 B'

// Display file size differences
prettyBytes(42, {signed: true});
//=> '+42 B'

// Localized output using German locale
prettyBytes(1337, {locale: 'de'});
//=> '1,34 kB'
```
*/
export default function prettyBytes(
	number: number | bigint,
	options?: Options
): string;