ArrayBuffer

The ArrayBuffer object is used to represent a generic, fixed-length raw binary data buffer.

It is an array of bytes, often referred to in other languages as a "byte array".

You cannot directly manipulate the contents of an ArrayBuffer; instead, you create one of the typed array objects or a DataView object which represents the buffer in a specific format, and use that to read and write the contents of the buffer.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

new ArrayBuffer(length)

Parameters

length

The size, in bytes, of the array buffer to create.

Return value

A new ArrayBuffer object of the specified size. Its contents are initialized to 0.

Exceptions

A RangeError is thrown if the length is larger than Number.MAX_SAFE_INTEGER (>= 2 ** 53) or negative.

Description

The ArrayBuffer constructor creates a new ArrayBuffer of the given length in bytes.

Getting an array buffer from existing data

• From a Base64 string
• From a local file

Properties

ArrayBuffer.length

The ArrayBuffer constructor's length property whose value is 1.

get ArrayBuffer[@@species]

The constructor function that is used to create derived objects.

ArrayBuffer.prototype

Allows the addition of properties to all ArrayBuffer objects.

Methods

ArrayBuffer.isView(arg)

Returns true if arg is one of the ArrayBuffer views, such as typed array objects or a DataView. Returns false otherwise.

ArrayBuffer.transfer(oldBuffer [, newByteLength])

Returns a new ArrayBuffer whose contents are taken from the oldBuffer's data and then is either truncated or zero-extended by newByteLength.

Instances

All ArrayBuffer instances inherit from ArrayBuffer.prototype.

Properties

ArrayBuffer.prototype.constructor

Specifies the function that creates an object's prototype. The initial value is the standard built-in ArrayBuffer constructor.

ArrayBuffer.prototype.byteLength Read only

The size, in bytes, of the array. This is established when the array is constructed and cannot be changed. Read only.

Methods

ArrayBuffer.prototype.slice()

Returns a new ArrayBuffer whose contents are a copy of this ArrayBuffer's bytes from begin, inclusive, up to end, exclusive. If either begin or end is negative, it refers to an index from the end of the array, as opposed to from the beginning.

ArrayBuffer.slice()

Has the same functionality as ArrayBuffer.prototype.slice().

Example

In this example, we create a 8-byte buffer with a Int32Array view referring to the buffer:

var buffer = new ArrayBuffer(8);
var view   = new Int32Array(buffer);

Specifications

Browser compatibility

Compatibility notes

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

var dv = ArrayBuffer(10);
// TypeError: calling a builtin ArrayBuffer constructor 
// without new is forbidden

var dv = new ArrayBuffer(10);

See also

• JavaScript typed arrays
• SharedArrayBuffer