DataView
The DataView
view provides a low-level interface for reading and writing multiple number types in a binary 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
Note: DataView
defaults to big-endian read and write, but most platforms use little-endian.
Constructor
DataView()
-
Creates a new
DataView
object.
Instance properties
These properties are defined on DataView.prototype
and shared by all DataView
instances.
DataView.prototype.buffer
-
The
ArrayBuffer
referenced by this view. Fixed at construction time and thus read only. DataView.prototype.byteLength
-
The length (in bytes) of this view. Fixed at construction time and thus read only.
DataView.prototype.byteOffset
-
The offset (in bytes) of this view from the start of its
ArrayBuffer
. Fixed at construction time and thus read only. DataView.prototype.constructor
-
The constructor function that created the instance object. For
DataView
instances, the initial value is theDataView
constructor. DataView.prototype[Symbol.toStringTag]
-
The initial value of the
[Symbol.toStringTag]
property is the string"DataView"
. This property is used inObject.prototype.toString()
.
Instance methods
DataView.prototype.getBigInt64()
-
Reads 8 bytes starting at the specified byte offset of this
DataView
and interprets them as a 64-bit signed integer. DataView.prototype.getBigUint64()
-
Reads 8 bytes starting at the specified byte offset of this
DataView
and interprets them as a 64-bit unsigned integer. 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. 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. 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. DataView.prototype.getInt16()
-
Reads 2 bytes starting at the specified byte offset of this
DataView
and interprets them as a 16-bit signed integer. DataView.prototype.getInt32()
-
Reads 4 bytes starting at the specified byte offset of this
DataView
and interprets them as a 32-bit signed integer. DataView.prototype.getInt8()
-
Reads 1 byte at the specified byte offset of this
DataView
and interprets it as an 8-bit signed integer. DataView.prototype.getUint16()
-
Reads 2 bytes starting at the specified byte offset of this
DataView
and interprets them as a 16-bit unsigned integer. DataView.prototype.getUint32()
-
Reads 4 bytes starting at the specified byte offset of this
DataView
and interprets them as a 32-bit unsigned integer. DataView.prototype.getUint8()
-
Reads 1 byte at the specified byte offset of this
DataView
and interprets it as an 8-bit unsigned integer. 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
. 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
. 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
. 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
. 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
. 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
. 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
. 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
. 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
. 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
. 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
Specification |
---|
ECMAScript Language Specification # sec-dataview-objects |
Browser compatibility
BCD tables only load in the browser