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DataView

The DataView view provides a low-level interface for reading data from and writing it to an ArrayBuffer.

Syntax

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

Parameters

buffer
An existing ArrayBuffer to use as the storage for the new DataView object.
byteOffset Optional
The offset, in bytes, to the first byte in the specified buffer for the new view to reference. If not specified, the view of the buffer will start with the first byte.
byteLength Optional
The number of elements in the byte array. If unspecified, length of the view will match the buffer's length.

Return value

A new DataView object representing the specified data buffer.

Errors thrown

RangeError
Thrown if the byteOffset and byteLength result in the specified view extending past the end of the buffer.

Description

Detect endianness

You'll probably need to detect the type of architecture your script is running, here is a little trick to check it. See Endianness for more information.

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

Properties

DataView.length
The DataView constructor's length property whose value is 3.
DataView.prototype
Allows the addition of properties to all DataView objects.

DataView instances

All DataView instances inherit from DataView.prototype.

Properties

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.

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.

Example

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

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

Specifications

Specification Status Comment
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'DataView' in that specification.
Standard Initial definition in an ECMA standard
Typed Array Specification Obsolete Superseded by ECMAScript 6

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 9.0 15.0 (15.0) 10 12.1 5.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 4.0 (Yes) 15.0 (15) ? 12.0 4.2

Firefox-specific notes

Starting with Gecko / SpiderMonkey 40 (Firefox 40 / Thunderbird 40 / SeaMonkey 2.37), 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.

Document Tags and Contributors

Last updated by: Sebastianz,
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