files/en-us/web/javascript/reference/global_objects/dataview/index.md

metadata

title: DataView
slug: Web/JavaScript/Reference/Global_Objects/DataView
page-type: javascript-class
browser-compat: javascript.builtins.DataView
sidebar: jsref

The DataView view provides a low-level interface for reading and writing multiple number types in a binary {{jsxref("ArrayBuffer")}}, without having to care about the platform's endianness.

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 is accessed, regardless of the executing computer's endianness. For example, WebAssembly memory is always little-endian, so you should use DataView instead of typed arrays to read and write multi-byte values. See WebAssembly.Memory for an example.

const littleEndian = (() => {
  const 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

DataView defaults to big-endian read and write, but most platforms use little-endian.

Constructor

• {{jsxref("DataView/DataView", "DataView()")}}
  • : Creates a new DataView object.

Instance properties

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

• {{jsxref("DataView.prototype.buffer")}}
  • : Returns the {{jsxref("ArrayBuffer")}} referenced by the DataView.
• {{jsxref("DataView.prototype.byteLength")}}
  • : Returns the length (in bytes) of the DataView.
• {{jsxref("DataView.prototype.byteOffset")}}
  • : Returns the offset (in bytes) of the DataView from the start of its {{jsxref("ArrayBuffer")}}.
• {{jsxref("Object/constructor", "DataView.prototype.constructor")}}
  • : The constructor function that created the instance object. For DataView instances, the initial value is the {{jsxref("DataView/DataView", "DataView")}} constructor.
• DataView.prototype[Symbol.toStringTag]
  • : The initial value of the [Symbol.toStringTag] property is the string "DataView". This property is used in {{jsxref("Object.prototype.toString()")}}.

Instance methods

• {{jsxref("DataView.prototype.getBigInt64()")}}
  • : Reads 8 bytes starting at the specified byte offset of this DataView and interprets them as a 64-bit signed integer.
• {{jsxref("DataView.prototype.getBigUint64()")}}
  • : Reads 8 bytes starting at the specified byte offset of this DataView and interprets them as a 64-bit unsigned integer.
• {{jsxref("DataView.prototype.getFloat16()")}}
  • : Reads 2 bytes starting at the specified byte offset of this DataView and interprets them as a 16-bit floating point number.
• {{jsxref("DataView.prototype.getFloat32()")}}
  • : Reads 4 bytes starting at the specified byte offset of this DataView and interprets them as a 32-bit floating point number.
• {{jsxref("DataView.prototype.getFloat64()")}}
  • : Reads 8 bytes starting at the specified byte offset of this DataView and interprets them as a 64-bit floating point number.
• {{jsxref("DataView.prototype.getInt16()")}}
  • : Reads 2 bytes starting at the specified byte offset of this DataView and interprets them as a 16-bit signed integer.
• {{jsxref("DataView.prototype.getInt32()")}}
  • : Reads 4 bytes starting at the specified byte offset of this DataView and interprets them as a 32-bit signed integer.
• {{jsxref("DataView.prototype.getInt8()")}}
  • : Reads 1 byte at the specified byte offset of this DataView and interprets it as an 8-bit signed integer.
• {{jsxref("DataView.prototype.getUint16()")}}
  • : Reads 2 bytes starting at the specified byte offset of this DataView and interprets them as a 16-bit unsigned integer.
• {{jsxref("DataView.prototype.getUint32()")}}
  • : Reads 4 bytes starting at the specified byte offset of this DataView and interprets them as a 32-bit unsigned integer.
• {{jsxref("DataView.prototype.getUint8()")}}
  • : Reads 1 byte at the specified byte offset of this DataView and interprets it as an 8-bit unsigned integer.
• {{jsxref("DataView.prototype.setBigInt64()")}}
  • : Takes a BigInt and stores it as a 64-bit signed integer in the 8 bytes starting at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setBigUint64()")}}
  • : Takes a BigInt and stores it as a 64-bit unsigned integer in the 8 bytes starting at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setFloat16()")}}
  • : Takes a number and stores it as a 16-bit float in the 2 bytes starting at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setFloat32()")}}
  • : Takes a number and stores it as a 32-bit float in the 4 bytes starting at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setFloat64()")}}
  • : Takes a number and stores it as a 64-bit float in the 8 bytes starting at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setInt16()")}}
  • : Takes a number and stores it as a 16-bit signed integer in the 2 bytes at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setInt32()")}}
  • : Takes a number and stores it as a 32-bit signed integer in the 4 bytes at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setInt8()")}}
  • : Takes a number and stores it as an 8-bit signed integer in the byte at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setUint16()")}}
  • : Takes a number and stores it as a 16-bit unsigned integer in the 2 bytes at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setUint32()")}}
  • : Takes a number and stores it as a 32-bit unsigned integer in the 4 bytes at the specified byte offset of this DataView.
• {{jsxref("DataView.prototype.setUint8()")}}
  • : Takes a number and stores it as an 8-bit unsigned integer in the byte at the specified byte offset of this DataView.

Examples

Using DataView

const buffer = new ArrayBuffer(16);
const view = new DataView(buffer, 0);

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

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• Polyfill of DataView in core-js
• {{jsxref("ArrayBuffer")}}
• {{jsxref("SharedArrayBuffer")}}