TypedArray

new TypedArray(length);
new TypedArray(typedArray);
new TypedArray(object);
new TypedArray(buffer [, byteOffset [, length]]);

where TypedArray() is one of:

Int8Array();
Uint8Array();
Uint8ClampedArray();
Int16Array();
Uint16Array();
Int32Array();
Uint32Array();
Float32Array();
Float64Array();

length

When called with a length argument, an internal array buffer is created in memory of size length multiplied by BYTES_PER_ELEMENT bytes containing 0 value.

typedArray

When called with a typedArray argument, which can be an object of any of the typed array types (such as Int32Array), the typedArray gets copied into a new typed array. Each value in typedArray is converted to the corresponding type of the constructor before being copied into the new array. Then length of the new typedArray object will be same of length of the typedArray argument.

object

When called with an object argument, a new typed array is created as if by the TypedArray.from() method.

buffer, byteOffset, length

When called with a buffer, and optionally a byteOffset and a length argument, a new typed array view is created that views the specified ArrayBuffer. The byteOffset and length parameters specify the memory range that will be exposed by the typed array view. If both are omitted, all of buffer is viewed; if only length is omitted, the remainder of buffer is viewed.

ECMAScript 2015 defines a TypedArray constructor that serves as the [[Prototype]] of all TypedArray constructors. This constructor is not directly exposed: there is no global %TypedArray% or TypedArray property. It is only directly accessible through Object.getPrototypeOf(Int8Array) and similar. All _TypedArray_s constructors inherit common properties from the %TypedArray% constructor function. Additionally, all typed array prototypes (TypedArray.prototype) have %TypedArray%.prototype as their [[Prototype]].

The %TypedArray% constructor on its own is not particularly useful. Calling it or using it in a new expression will throw a TypeError, except when used during object creation in JS engines that support subclassing. There are at present no such engines, so %TypedArray% is only useful to polyfill functions or properties onto all TypedArray constructors.

When creating a TypedArray instance (i.e. instance of Int8Array or similar), an array buffer is created internally (if ArrayBuffer object is present as constructor argument then this array buffer is used) in memory and this buffer address is saved as internal property of that instances, and all the methods of %TypedArray%.prototype uses that array buffer address to operate on i.e. set value and get value etc.

You can reference elements in the array using standard array index syntax (that is, using bracket notation). However, getting or setting indexed properties on typed arrays will not search in the prototype chain for this property, even when the indices are out of bound. Indexed properties will consult the ArrayBuffer and will never look at object properties. You can still use named properties, just like with all objects.

// Setting and getting using standard array syntax
var int16 = new Int16Array(2);
int16[0] = 42;
console.log(int16[0]); // 42

// Indexed properties on prototypes are not consulted (Fx 25)
Int8Array.prototype[20] = 'foo';
(new Int8Array(32))[20]; // 0
// even when out of bound
Int8Array.prototype[20] = 'foo';
(new Int8Array(8))[20]; // undefined
// or with negative integers
Int8Array.prototype[-1] = 'foo';
(new Int8Array(8))[-1]; // undefined

// Named properties are allowed, though (Fx 30)
Int8Array.prototype.foo = 'bar';
(new Int8Array(32)).foo; // "bar"

TypedArray.BYTES_PER_ELEMENT (en-US)

Returns a number value of the element size for the different typed array objects.

TypedArray.length

Length property whose value is 0.

TypedArray.name (en-US)

Returns the string value of the constructor name. E.g "Int8Array".

get TypedArray[@@species] (en-US)

The constructor function that is used to create derived objects.

TypedArray.prototype (en-US)

Prototype for the TypedArray objects.

TypedArray.from() (en-US)

Creates a new typed array from an array-like or iterable object. See also Array.from().

TypedArray.of() (en-US)

Creates a new typed array with a variable number of arguments. See also Array.of().

All TypedArrays inherit from TypedArray.prototype (en-US).

Starting with ECMAScript 2015, TypedArray constructors require to be constructed with a new operator. Calling a TypedArray constructor as a function without new, will throw a TypeError from now on.

var dv = Int8Array([1, 2, 3]);
// TypeError: calling a builtin Int8Array constructor
// without new is forbidden

var dv = new Int8Array([1, 2, 3]);

• JavaScript typed arrays
• ArrayBuffer
• DataView