JavaScript Uint8Array : Object

constructor

Uint8Array is similar to an Array where each item is an 8 bit (1 byte) unsigned integer. Uint8Arrays cannot change size after creation.

Spec

Constructors

new Uint8Array(length : Number) : Uint8Array

Creates a new Uint8Array of the specified length where each item starts out as 0

Example:

var x = new Uint8Array(2);
x[0] = 17;
console.log(x[0]);
console.log(x[1]);
console.log(x.length);

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Results:

new Uint8Array(array : Array) : Uint8Array

Creates a new Uint8Array and copies the items of array into this. The copied items are converted to 8 bit unsigned integers before being stored in this.

Example:

var x = new Uint8Array([17, -45.3]);
console.log(x[0]);
console.log(x[1]);
console.log(x.length);

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Results:

new Uint8Array(array : Uint8Array) : Uint8Array

Creates a new Uint8Array and copies the items of array into this. array can be any of the typed array types and the copied items will be converted to 8 bit unsigned integers before being stored in this.

Example:

var x = new Uint8Array([17, -45.3]);
var y = new Uint8Array(x);
console.log(x[0]);
console.log(x[1]);
console.log(x.length);
x[0] = -2;
console.log(y[0]); // y is not modified

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Results:

new Uint8Array(buffer : ArrayBuffer, [byteOffset = 0 : Number, [length : Number]]) : Uint8Array

Creates a view on top of the specified buffer starting at byteOffset of length items. Changes to the items in this actual affect the underlying buffer, and vice versa. If length is not specified, the length will be buffer.length - byteOffset.

Example:

var buffer = new ArrayBuffer(12);
var x = new Uint8Array(buffer, 0);
// Make another view of 5th to 7th bytes of the buffer
var y = new Uint8Array(buffer, 4, 2);
x[4] = 4;
console.log(y[0]); // y is a live view on the buffer

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Results:

Instance Properties

buffer : ArrayBuffer

Returns the underlying buffer for this Uint8Array.

Example:

var buffer = new ArrayBuffer(12);
var x = new Uint8Array(buffer, 0, 2);
var y = new Uint8Array(x.buffer, 4, 2);
console.log(x.buffer === y.buffer);

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Results:

byteLength : Number

The length of this in bytes.

Example:

var buffer = new ArrayBuffer(12);
var x = new Uint8Array(buffer, 4, 2);
console.log(x.byteLength); 
console.log(x.length * Uint8Array.BYTES_PER_ELEMENT);

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Results:

byteOffset : Number

The offset into this.buffer where the 0th item is stored.

Example:

var buffer = new ArrayBuffer(12);
var x = new Uint8Array(buffer, 4, 2);
console.log(x.byteOffset);

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Results:

length : Number

The number of elements in this. It is 1 greater than the index of the last item.

Example:

var x = new Uint8Array(10);
console.log(x.length);

Run

Results:

Instance Methods

set 2 variants

set(array : Array, [offset = 0 : Number]) : undefined

Copies items from array into this starting at this[offset]. Copied items are converted to 8 bit unsigned integers before storing in this.

Example:

var x = new Uint8Array(10);
x.set([18, 93, 42], 3);
console.log(x[3]);
console.log(x[4]);
console.log(x[5]);

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Results:

set(array : Uint8Array, [offset = 0 : Number]) : undefined

Copies items from array into this starting at this[offset]. array can be any of the typed array types and the copied items will be converted to 8 bit unsigned integers before storing in this.

Example:

var x = new Uint8Array(10);
x.set(new Uint8Array([18, 93, 42]), 3);
console.log(x[3]);
console.log(x[4]);
console.log(x[5]);

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Results:

subarray(begin : Number, [end : Number]) : Uint8Array

Returns a new Uint8Array that is a view on top of this containing items this[begin], this[begin + 1], ..., this[end - 1]. The 0th item in the returned array in the same memory location as this[begin]. If end is not specified, this.length is used.

Example:

var x = new Uint8Array([0, 1, 2, 3, 4, 5]); // length=6
var y = x.subarray(2, 5);
console.log(y.length);
console.log(y[0]);
console.log(y[1]);
y[0] = -1;
console.log(x[2]);

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Results:

Uint8Array Properties

BYTES_PER_ELEMENT : Number

Returns the size in bytes of an item in an Uint8Array.

Example:

console.log(Uint8Array.BYTES_PER_ELEMENT);

Run

Results:

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