ArrayBuffer

The ArrayBuffer object is used to represent a generic 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 ArrayBuffer() constructor creates a new ArrayBuffer of the given length in bytes. You can also get an array buffer from existing data, for example, from a Base64 string or from a local file .

ArrayBuffer is a transferable object .

Description

Resizing ArrayBuffers

ArrayBuffer objects can be made resizable by including the maxByteLength option when calling the ArrayBuffer() constructor. You can query whether an ArrayBuffer is resizable and what its maximum size is by accessing its resizable and maxByteLength properties, respectively. You can assign a new size to a resizable ArrayBuffer with a resize() call. New bytes are initialized to 0.

These features make resizing ArrayBuffer s more efficient — otherwise, you have to make a copy of the buffer with a new size. It also gives JavaScript parity with WebAssembly in this regard (Wasm linear memory can be resized with WebAssembly.Memory.prototype.grow() ).

Constructor

ArrayBuffer()

Creates a new ArrayBuffer object.

Static properties

ArrayBuffer[@@species]

The constructor function that is used to create derived objects.

Static methods

ArrayBuffer.isView()

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

Instance properties

These properties are defined on ArrayBuffer.prototype and shared by all ArrayBuffer instances.

ArrayBuffer.prototype.byteLength

The size, in bytes, of the ArrayBuffer . This is established when the array is constructed and can only be changed using the ArrayBuffer.prototype.resize() method if the ArrayBuffer is resizable.

ArrayBuffer.prototype.constructor

The constructor function that created the instance object. For ArrayBuffer instances, the initial value is the ArrayBuffer constructor.

ArrayBuffer.prototype.maxByteLength

The read-only maximum length, in bytes, that the ArrayBuffer can be resized to. This is established when the array is constructed and cannot be changed.

ArrayBuffer.prototype.resizable

Read-only. Returns true if the ArrayBuffer can be resized, or false if not.

ArrayBuffer.prototype[@@toStringTag]

The initial value of the @@toStringTag property is the string "ArrayBuffer" . This property is used in Object.prototype.toString() .

Instance methods

ArrayBuffer.prototype.resize()

Resizes the ArrayBuffer to the specified size, in bytes.

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.

Examples

Creating an ArrayBuffer

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

js 

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