uint8array-extras

Useful utilities for working with Uint8Array (and Buffer)

It's time to transition from Buffer to Uint8Array, and this package helps fill in the gaps.

Note that Buffer is a Uint8Array subclass, so you can use this package with Buffer too.

This package is tree-shakeable and browser-compatible.

This package also includes methods to convert a string to Base64 and back.

Note: In the browser, do not use globalThis.atob() / globalThis.btoa() because they do not support Unicode. This package does.

Install

npm install uint8array-extras

Usage

import {concatUint8Arrays} from 'uint8array-extras';

const a = new Uint8Array([1, 2, 3]);
const b = new Uint8Array([4, 5, 6]);

console.log(concatUint8Arrays([a, b]));
//=> Uint8Array [1, 2, 3, 4, 5, 6]

API

isUint8Array(value: unknown): boolean

Check if the given value is an instance of Uint8Array.

Replacement for Buffer.isBuffer().

import {isUint8Array} from 'uint8array-extras';

console.log(isUint8Array(new Uint8Array()));
//=> true

console.log(isUint8Array(Buffer.from('x')));
//=> true

console.log(isUint8Array(new ArrayBuffer(10)));
//=> false

assertUint8Array(value: unknown)

Throw a TypeError if the given value is not an instance of Uint8Array.

import {assertUint8Array} from 'uint8array-extras';

try {
	assertUint8Array(new ArrayBuffer(10)); // Throws a TypeError
} catch (error) {
	console.error(error.message);
}

assertUint8ArrayOrArrayBuffer(value: unknown)

Throw a TypeError if the given value is not an instance of Uint8Array or ArrayBuffer.

Useful as a guard for functions that accept either a Uint8Array or ArrayBuffer.

import {assertUint8ArrayOrArrayBuffer} from 'uint8array-extras';

assertUint8ArrayOrArrayBuffer(new Uint8Array());
assertUint8ArrayOrArrayBuffer(new ArrayBuffer(8));

toUint8Array(value: TypedArray | ArrayBuffer | DataView): Uint8Array

Convert a value to a Uint8Array without copying its data.

This can be useful for converting a Buffer to a pure Uint8Array. Buffer is already a Uint8Array subclass, but Buffer alters some behavior, so it can be useful to cast it to a pure Uint8Array before returning it.

Tip: If you want a copy, just call .slice() on the return value.

concatUint8Arrays(arrays: Array<Uint8Array | ArrayBuffer>, totalLength?: number): Uint8Array

Concatenate the given arrays into a new array.

If arrays is empty, it will return a zero-sized Uint8Array.

If totalLength is not specified, it is calculated from summing the lengths of the given arrays.

Replacement for Buffer.concat().

import {concatUint8Arrays} from 'uint8array-extras';

const a = new Uint8Array([1, 2, 3]);
const b = new Uint8Array([4, 5, 6]);

console.log(concatUint8Arrays([a, b]));
//=> Uint8Array [1, 2, 3, 4, 5, 6]

areUint8ArraysEqual(a: Uint8Array | ArrayBuffer, b: Uint8Array | ArrayBuffer): boolean

Check if two arrays are identical by verifying that they contain the same bytes in the same sequence.

Replacement for Buffer#equals().

import {areUint8ArraysEqual} from 'uint8array-extras';

const a = new Uint8Array([1, 2, 3]);
const b = new Uint8Array([1, 2, 3]);
const c = new Uint8Array([4, 5, 6]);

console.log(areUint8ArraysEqual(a, b));
//=> true

console.log(areUint8ArraysEqual(a, c));
//=> false

compareUint8Arrays(a: Uint8Array | ArrayBuffer, b: Uint8Array | ArrayBuffer): 0 | 1 | -1

Compare two arrays and indicate their relative order or equality. Useful for sorting.

Replacement for Buffer.compare().

import {compareUint8Arrays} from 'uint8array-extras';

const array1 = new Uint8Array([1, 2, 3]);
const array2 = new Uint8Array([4, 5, 6]);
const array3 = new Uint8Array([7, 8, 9]);

[array3, array1, array2].sort(compareUint8Arrays);
//=> [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

uint8ArrayToString(array: Uint8Array | ArrayBuffer, encoding?: string = 'utf8'): string

Convert a Uint8Array to a string.

• Parameter: encoding - The encoding to convert from.

Replacement for Buffer#toString(). For the encoding parameter, latin1 should be used instead of binary and utf-16le instead of utf16le.

import {uint8ArrayToString} from 'uint8array-extras';

const byteArray = new Uint8Array([72, 101, 108, 108, 111]);
console.log(uint8ArrayToString(byteArray));
//=> 'Hello'

const zh = new Uint8Array([167, 65, 166, 110]);
console.log(uint8ArrayToString(zh, 'big5'));
//=> '你好'

const ja = new Uint8Array([130, 177, 130, 241, 130, 201, 130, 191, 130, 205]);
console.log(uint8ArrayToString(ja, 'shift-jis'));
//=> 'こんにちは'

stringToUint8Array(string: string): Uint8Array

Convert a string to a Uint8Array (using UTF-8 encoding).

Replacement for Buffer.from('Hello').

import {stringToUint8Array} from 'uint8array-extras';

console.log(stringToUint8Array('Hello'));
//=> Uint8Array [72, 101, 108, 108, 111]

uint8ArrayToBase64(array: Uint8Array | ArrayBuffer, options?: {urlSafe: boolean}): string

Convert a Uint8Array to a Base64-encoded string.

Specify {urlSafe: true} to get a Base64URL-encoded string.

Replacement for Buffer#toString('base64').

import {uint8ArrayToBase64} from 'uint8array-extras';

const byteArray = new Uint8Array([72, 101, 108, 108, 111]);

console.log(uint8ArrayToBase64(byteArray));
//=> 'SGVsbG8='

base64ToUint8Array(string: string): Uint8Array

Convert a Base64-encoded or Base64URL-encoded string to a Uint8Array.

Accepts Base64URL with or without padding.

Replacement for Buffer.from('SGVsbG8=', 'base64').

import {base64ToUint8Array} from 'uint8array-extras';

console.log(base64ToUint8Array('SGVsbG8='));
//=> Uint8Array [72, 101, 108, 108, 111]

stringToBase64(string: string, options?: {urlSafe: boolean}): string

Encode a string to a Base64-encoded string.

Specify {urlSafe: true} to get a Base64URL-encoded string.

Replacement for Buffer.from('Hello').toString('base64') and btoa().

import {stringToBase64} from 'uint8array-extras';

console.log(stringToBase64('Hello'));
//=> 'SGVsbG8='

base64ToString(base64String: string): string

Decode a Base64-encoded or Base64URL-encoded string to a string.

Accepts Base64URL with or without padding.

Replacement for Buffer.from('SGVsbG8=', 'base64').toString() and atob().

import {base64ToString} from 'uint8array-extras';

console.log(base64ToString('SGVsbG8='));
//=> 'Hello'

uint8ArrayToHex(array: Uint8Array | ArrayBuffer): string

Convert a Uint8Array to a Hex string.

Replacement for Buffer#toString('hex').

import {uint8ArrayToHex} from 'uint8array-extras';

const byteArray = new Uint8Array([72, 101, 108, 108, 111]);

console.log(uint8ArrayToHex(byteArray));
//=> '48656c6c6f'

hexToUint8Array(hexString: string): Uint8Array

Convert a Hex string to a Uint8Array.

Replacement for Buffer.from('48656c6c6f', 'hex').

import {hexToUint8Array} from 'uint8array-extras';

console.log(hexToUint8Array('48656c6c6f'));
//=> Uint8Array [72, 101, 108, 108, 111]

getUintBE(view: DataView): number

Read DataView#byteLength number of bytes from the given view, up to 48-bit.

Replacement for Buffer#readUIntBE

import {getUintBE} from 'uint8array-extras';

const byteArray = new Uint8Array([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(getUintBE(new DataView(byteArray.buffer)));
//=> 20015998341291

indexOf(array: Uint8Array | ArrayBuffer, value: Uint8Array | ArrayBuffer): number

Find the index of the first occurrence of the given sequence of bytes (value) within the given Uint8Array (array).

Replacement for Buffer#indexOf. Uint8Array#indexOf only takes a number which is different from Buffer's indexOf implementation.

import {indexOf} from 'uint8array-extras';

const byteArray = new Uint8Array([0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef]);

console.log(indexOf(byteArray, new Uint8Array([0x78, 0x90])));
//=> 3

includes(array: Uint8Array | ArrayBuffer, value: Uint8Array | ArrayBuffer): boolean

Checks if the given sequence of bytes (value) is within the given Uint8Array (array).

Returns true if the value is included, otherwise false.

Replacement for Buffer#includes. Uint8Array#includes only takes a number which is different from Buffer's includes implementation.

import {includes} from 'uint8array-extras';

const byteArray = new Uint8Array([0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef]);

console.log(includes(byteArray, new Uint8Array([0x78, 0x90])));
//=> true