Uint8Array() constructor

Baseline Widely available

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

The Uint8Array() constructor creates Uint8Array objects. The contents are initialized to 0.

Syntax

js
new Uint8Array()
new Uint8Array(length)
new Uint8Array(typedArray)
new Uint8Array(object)

new Uint8Array(buffer)
new Uint8Array(buffer, byteOffset)
new Uint8Array(buffer, byteOffset, length)

Note: Uint8Array() can only be constructed with new. Attempting to call it without new throws a TypeError.

Parameters

See TypedArray.

Exceptions

See TypedArray.

Examples

Different ways to create a Uint8Array

js
// From a length
const uint8 = new Uint8Array(2);
uint8[0] = 42;
console.log(uint8[0]); // 42
console.log(uint8.length); // 2
console.log(uint8.BYTES_PER_ELEMENT); // 1

// From an array
const x = new Uint8Array([21, 31]);
console.log(x[1]); // 31

// From another TypedArray
const y = new Uint8Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
const buffer = new ArrayBuffer(8);
const z = new Uint8Array(buffer, 1, 4);
console.log(z.byteOffset); // 1

// From an iterable
const iterable = (function* () {
  yield* [1, 2, 3];
})();
const uint8FromIterable = new Uint8Array(iterable);
console.log(uint8FromIterable);
// Uint8Array [1, 2, 3]

Specifications

Specification
ECMAScript Language Specification
# sec-typedarray-constructors

Browser compatibility

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See also