DataView

DataView provee una interfaz de bajo nivel para la lectura y escritura de diferentes tipos de números dentro de un ArrayBuffer sin importar el endianness de la plataforma.

El código fuente de este ejemplo interactivo se encuentra almacenado en un repositorio en Github. Si te interesa contribuir al proyecto de ejemplos interactivos, por favor clona https://github.com/mdn/interactive-examples y envíanos un pull request.

Sintaxis

new DataView(buffer [, byteOffset [, byteLength]])

Parámetros

buffer

Un ArrayBuffer o SharedArrayBuffer  existente que será utilizado por el nuevo objeto DataView.

byteOffset Optional

El desplazamiento, en bytes, desde el primer byte en el buffer, que servirá como referencia para iniciar la nueva vista. Si no es especificado, la vista comenzará con el primer byte del buffer.

byteLength Optional

El número de elementos en el array de bytes. Si no es especificado, el tamaño de la vista será el mismo tamaño del buffer.

Valor retornado

Un nuevo objeto DataView representando el buffer de datos especificado.

Excepciones

RangeError

Esta excepción es lanzada si el byteOffset y el byteLength resultante en la nueva vista sobrepasan el final del buffer.

Description

Endianness

Multi-byte number formats are represented in memory differently depending on machine architecture, see Endianness for an explanation. DataView accessors provide explicit control of how data will be accessed irrespective of the platform architecture's endianness.

var littleEndian = (function() {
  var buffer = new ArrayBuffer(2);
  new DataView(buffer).setInt16(0, 256, true /* littleEndian */);
  // Int16Array uses the platform's endianness.
  return new Int16Array(buffer)[0] === 256;
})();
console.log(littleEndian); // true or false

Properties

All DataView instances inherit from DataView.prototype and allows the addition of properties to all DataView objects.

DataView.prototype.constructor

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

DataView.prototype.buffer Read only

The ArrayBuffer referenced by this view. Fixed at construction time and thus read only.

DataView.prototype.byteLength Read only

The length (in bytes) of this view from the start of its ArrayBuffer. Fixed at construction time and thus read only.

DataView.prototype.byteOffset Read only

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

Methods

Read

DataView.prototype.getInt8()

Gets a signed 8-bit integer (byte) at the specified byte offset from the start of the view.

DataView.prototype.getUint8()

Gets an unsigned 8-bit integer (unsigned byte) at the specified byte offset from the start of the view.

DataView.prototype.getInt16()

Gets a signed 16-bit integer (short) at the specified byte offset from the start of the view.

DataView.prototype.getUint16()

Gets an unsigned 16-bit integer (unsigned short) at the specified byte offset from the start of the view.

DataView.prototype.getInt32()

Gets a signed 32-bit integer (long) at the specified byte offset from the start of the view.

DataView.prototype.getUint32()

Gets an unsigned 32-bit integer (unsigned long) at the specified byte offset from the start of the view.

DataView.prototype.getFloat32()

Gets a signed 32-bit float (float) at the specified byte offset from the start of the view.

DataView.prototype.getFloat64()

Gets a signed 64-bit float (double) at the specified byte offset from the start of the view.

DataView.prototype.getBigInt64()

Gets a signed 64-bit integer (long long) at the specified byte offset from the start of the view.

DataView.prototype.getBigUint64()

Gets an unsigned 64-bit integer (unsigned long long) at the specified byte offset from the start of the view.

Write

DataView.prototype.setInt8()

Stores a signed 8-bit integer (byte) value at the specified byte offset from the start of the view.

DataView.prototype.setUint8()

Stores an unsigned 8-bit integer (unsigned byte) value at the specified byte offset from the start of the view.

DataView.prototype.setInt16()

Stores a signed 16-bit integer (short) value at the specified byte offset from the start of the view.

DataView.prototype.setUint16()

Stores an unsigned 16-bit integer (unsigned short) value at the specified byte offset from the start of the view.

DataView.prototype.setInt32()

Stores a signed 32-bit integer (long) value at the specified byte offset from the start of the view.

DataView.prototype.setUint32()

Stores an unsigned 32-bit integer (unsigned long) value at the specified byte offset from the start of the view.

DataView.prototype.setFloat32()

Stores a signed 32-bit float (float) value at the specified byte offset from the start of the view.

DataView.prototype.setFloat64()

Stores a signed 64-bit float (double) value at the specified byte offset from the start of the view.

DataView.prototype.setBigInt64()

Stores a signed 64-bit integer (long long) value at the specified byte offset from the start of the view.

DataView.prototype.setBigUint64()

Stores an unsigned 64-bit integer (unsigned long long) value at the specified byte offset from the start of the view.

Example

var buffer = new ArrayBuffer(16);
var dv = new DataView(buffer, 0);

dv.setInt16(1, 42);
dv.getInt16(1); //42

Specifications

Browser compatibility

Compatibility notes

Starting with Firefox 40, DataView requires to be constructed with a new operator. Calling DataView() as a function without new, will throw a TypeError from now on.

var dv = DataView(buffer, 0); 
// TypeError: calling a builtin DataView constructor without new is forbidden

var dv = new DataView(buffer, 0);

See also

• jDataView: JavaScript library that polyfills and extends the DataView API to all browsers and Node.js.
• ArrayBuffer
• SharedArrayBuffer