Uint8Array

BaselineWidely available *

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

* Some parts of this feature may have varying levels of support.

TheUint8Array typed array represents an array of 8-bit unsigned integers. The contents are initialized to0 unless initialization data is explicitly provided. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).

Uint8Array is a subclass of the hiddenTypedArray class.

Description

Uint8Array is currently the onlyTypedArray subclass that has additional methods compared to other typed arrays. Because of its nature as a generic byte array, it is the most suitable for working with arbitrary binary data. It supports two sets of methods for the creation, serialization, and modification ofUint8Array data to/from hex strings and base64 strings.

Uint8Array.fromBase64(),Uint8Array.prototype.toBase64(), andUint8Array.prototype.setFromBase64() for working withbase64 strings, where 3 bytes are encoded by 4 characters that are either 0–9, A–Z, a–z, "+", and "/" (or "-" and "_", if using URL-safe base64).
Uint8Array.fromHex(),Uint8Array.prototype.toHex(), andUint8Array.prototype.setFromHex() for working with hex strings, where every byte is encoded by two characters, each one being either 0–9 or A–F (case-insensitive).

Constructor

Uint8Array(): Creates a newUint8Array object.

Static properties

Also inherits static properties from its parentTypedArray.

Uint8Array.BYTES_PER_ELEMENT: Returns a number value of the element size.1 in the case ofUint8Array.

Static methods

Inherits static methods from its parentTypedArray.

Uint8Array.fromBase64(): Creates a newUint8Array object from a base64-encoded string.
Uint8Array.fromHex(): Creates a newUint8Array object from a hex-encoded string.

Instance properties

Also inherits instance properties from its parentTypedArray.

These properties are defined onUint8Array.prototype and shared by allUint8Array instances.

Uint8Array.prototype.BYTES_PER_ELEMENT: Returns a number value of the element size.1 in the case of aUint8Array.
Uint8Array.prototype.constructor: The constructor function that created the instance object. ForUint8Array instances, the initial value is theUint8Array constructor.

Instance methods

Inherits instance methods from its parentTypedArray.

Uint8Array.prototype.setFromBase64(): Populates thisUint8Array object with bytes from a base64-encoded string, returning an object indicating how many bytes were read and written.
Uint8Array.prototype.setFromHex(): Populates thisUint8Array object with bytes from a hex-encoded string, returning an object indicating how many bytes were read and written.
Uint8Array.prototype.toBase64(): Returns a base64-encoded string based on the data in thisUint8Array object.
Uint8Array.prototype.toHex(): Returns a hex-encoded string based on the data in thisUint8Array object.

Examples

Different ways to create a Uint8Array

// From a lengthconst uint8 = new Uint8Array(2);uint8[0] = 42;console.log(uint8[0]); // 42console.log(uint8.length); // 2console.log(uint8.BYTES_PER_ELEMENT); // 1// From an arrayconst x = new Uint8Array([21, 31]);console.log(x[1]); // 31// From another TypedArrayconst y = new Uint8Array(x);console.log(y[0]); // 21// From an ArrayBufferconst buffer = new ArrayBuffer(8);const z = new Uint8Array(buffer, 1, 4);console.log(z.byteOffset); // 1// From an iterableconst iterable = (function* () {  yield* [1, 2, 3];})();const uint8FromIterable = new Uint8Array(iterable);console.log(uint8FromIterable);// Uint8Array [1, 2, 3]