Uint8Array

The Uint8Array typed array represents an array of 8-bit unsigned integers. The contents are initialized to 0. 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).

Syntax

new Uint8Array(); // new in ES2017
new Uint8Array(length);
new Uint8Array(typedArray);
new Uint8Array(object);
new Uint8Array(buffer [, byteOffset [, length]]);

For more information about the constructor syntax and the parameters, see TypedArray.

Properties

Uint8Array.BYTES_PER_ELEMENT

Returns a number value of the element size. 1 in the case of an Uint8Array.

Uint8Array.length

Static length property whose value is 0. For the actual length (number of elements), see Uint8Array.prototype.length.

Uint8Array.name

Returns the string value of the constructor name. In the case of the Uint8Array type: "Uint8Array".

Uint8Array.prototype

Prototype for the TypedArray objects.

Methods

Uint8Array.from()

Creates a new Uint8Array from an array-like or iterable object. See also Array.from().

Uint8Array.of()

Creates a new Uint8Array with a variable number of arguments. See also Array.of().

Uint8Array prototype

All Uint8Array objects inherit from %TypedArray%.prototype.

Properties

Uint8Array.prototype.constructor

Returns the function that created an instance's prototype. This is the Uint8Array constructor by default.

Uint8Array.prototype.buffer Read only

Returns the ArrayBuffer referenced by the Uint8Array Fixed at construction time and thus read only.

Uint8Array.prototype.byteLength Read only

Returns the length (in bytes) of the Uint8Array. Fixed at construction time and thus read only.

Uint8Array.prototype.byteOffset Read only

Returns the offset (in bytes) of the Uint8Array from the start of its ArrayBuffer. Fixed at construction time and thus read only.

Uint8Array.prototype.length Read only

Returns the number of elements held in the Uint8Array. Fixed at construction time and thus read only.

Methods

Uint8Array.prototype.copyWithin()

Copies a sequence of array elements within the array. See also Array.prototype.copyWithin().

Uint8Array.prototype.entries()

Returns a new Array Iterator object that contains the key/value pairs for each index in the array. See also Array.prototype.entries().

Uint8Array.prototype.every()

Tests whether all elements in the array pass the test provided by a function. See also Array.prototype.every().

Uint8Array.prototype.fill()

Fills all the elements of an array from a start index to an end index with a static value. See also Array.prototype.fill().

Uint8Array.prototype.filter()

Creates a new array with all of the elements of this array for which the provided filtering function returns true. See also Array.prototype.filter().

Uint8Array.prototype.find()

Returns the found value in the array, if an element in the array satisfies the provided testing function or undefined if not found. See also Array.prototype.find().

Uint8Array.prototype.findIndex()

Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found. See also Array.prototype.findIndex().

Uint8Array.prototype.forEach()

Calls a function for each element in the array. See also Array.prototype.forEach().

Uint8Array.prototype.includes()

Determines whether a typed array includes a certain element, returning true or false as appropriate. See also Array.prototype.includes().

Uint8Array.prototype.indexOf()

Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.indexOf().

Uint8Array.prototype.join()

Joins all elements of an array into a string. See also Array.prototype.join().

Uint8Array.prototype.keys()

Returns a new Array Iterator that contains the keys for each index in the array. See also Array.prototype.keys().

Uint8Array.prototype.lastIndexOf()

Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.lastIndexOf().

Uint8Array.prototype.map()

Creates a new array with the results of calling a provided function on every element in this array. See also Array.prototype.map().

Uint8Array.prototype.move() Unimplemented

Former non-standard version of Uint8Array.prototype.copyWithin().

Uint8Array.prototype.reduce()

Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value. See also Array.prototype.reduce().

Uint8Array.prototype.reduceRight()

Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value. See also Array.prototype.reduceRight().

Uint8Array.prototype.reverse()

Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. See also Array.prototype.reverse().

Uint8Array.prototype.set()

Stores multiple values in the typed array, reading input values from a specified array.

Uint8Array.prototype.slice()

Extracts a section of an array and returns a new array. See also Array.prototype.slice().

Uint8Array.prototype.some()

Returns true if at least one element in this array satisfies the provided testing function. See also Array.prototype.some().

Uint8Array.prototype.sort()

Sorts the elements of an array in place and returns the array. See also Array.prototype.sort().

Uint8Array.prototype.subarray()

Returns a new Uint8Array from the given start and end element index.

Uint8Array.prototype.values()

Returns a new Array Iterator object that contains the values for each index in the array. See also Array.prototype.values().

Uint8Array.prototype.toLocaleString()

Returns a localized string representing the array and its elements. See also Array.prototype.toLocaleString().

Uint8Array.prototype.toString()

Returns a string representing the array and its elements. See also Array.prototype.toString().

Uint8Array.prototype[@@iterator]()

Returns a new Array Iterator object that contains the values for each index in the array.

Examples

Different ways to create a Uint8Array:

// From a length
var 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
var arr = new Uint8Array([21,31]);
console.log(arr[1]); // 31

// From another TypedArray
var x = new Uint8Array([21, 31]);
var y = new Uint8Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
var buffer = new ArrayBuffer(8);
var z = new Uint8Array(buffer, 1, 4);

// From an iterable 
var iterable = function*(){ yield* [1,2,3]; }(); 
var uint8 = new Uint8Array(iterable); 
// Uint8Array[1, 2, 3]

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Compatibility notes

Starting with ECMAScript 2015, Uint8Array constructors require to be constructed with a new operator. Calling a Uint8Array constructor as a function without new, will throw a TypeError from now on.

var dv = Uint8Array([1, 2, 3]);
// TypeError: calling a builtin Uint8Array constructor
// without new is forbidden

var dv = new Uint8Array([1, 2, 3]);

See also

• JavaScript typed arrays
• ArrayBuffer
• DataView