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TypedArray

A TypedArray object describes an array-like view of an underlying binary data buffer. There is no global property named TypedArray, nor is there a directly visible TypedArray constructor. Instead, there are a number of different global properties, whose values are typed array constructors for specific element types, listed below. On the following pages you will find common properties and methods that can be used with any typed array containing elements of any type.

Description

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 TypedArrays 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 an instance of a TypedArray (e.g. Int8Array), an array buffer is created internally in memory or, if an ArrayBuffer object is given as constructor argument, then this is used instead. The buffer address is saved as an internal property of the instance and all the methods of %TypedArray%.prototype, i.e. set value and get value etc., operate on that array buffer address.

TypedArray objects

Type Value Range Size in bytes Description Web IDL type Equivalent C type
Int8Array -128 to 127 1 8-bit two's complement signed integer byte int8_t
Uint8Array 0 to 255 1 8-bit unsigned integer octet uint8_t
Uint8ClampedArray 0 to 255 1 8-bit unsigned integer (clamped) octet uint8_t
Int16Array -32768 to 32767 2 16-bit two's complement signed integer short int16_t
Uint16Array 0 to 65535 2 16-bit unsigned integer unsigned short uint16_t
Int32Array -2147483648 to 2147483647 4 32-bit two's complement signed integer long int32_t
Uint32Array 0 to 4294967295 4 32-bit unsigned integer unsigned long uint32_t
Float32Array 1.2×10-38 to 3.4×1038 4 32-bit IEEE floating point number (7 significant digits e.g., 1.1234567) unrestricted float float
Float64Array 5.0×10-324 to 1.8×10308 8 64-bit IEEE floating point number (16 significant digits e.g., 1.123...15) unrestricted double double
BigInt64Array -263 to 263-1 8 64-bit two's complement signed integer bigint int64_t (signed long long)
BigUint64Array 0 to 264-1 8 64-bit unsigned integer bigint uint64_t (unsigned long long)

Constructor

This object cannot be instantiated directly. Instead, you create an instance of an array of a particular type, such as a Int8Array or a BigInt64Array. These objects all have a common syntax for their constructors:

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

Where TypedArray is a constructor for one of the concrete types.

Parameters

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 zeros.
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. The length of the new typed array will be same as the 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.

Static properties

TypedArray.BYTES_PER_ELEMENT
Returns a number value of the element size for the different TypedArray objects.
TypedArray.name
Returns the string value of the constructor name (e.g, "Int8Array").
get TypedArray[@@species]
The constructor function used to create derived objects.
TypedArray.prototype
Prototype for TypedArray objects.

Static methods

TypedArray.from()
Creates a new TypedArray from an array-like or iterable object. See also Array.from().
TypedArray.of()
Creates a new TypedArray with a variable number of arguments. See also Array.of().

Instance properties

TypedArray.prototype.buffer
Returns the ArrayBuffer referenced by the typed array. Fixed at construction time and thus read only.
TypedArray.prototype.byteLength
Returns the length (in bytes) of the typed array. Fixed at construction time and thus read only.
TypedArray.prototype.byteOffset
Returns the offset (in bytes) of the typed array from the start of its ArrayBuffer. Fixed at construction time and thus read only.
TypedArray.prototype.length
Returns the number of elements held in the typed array. Fixed at construction time and thus read only.

Instance methods

TypedArray.prototype.copyWithin()
Copies a sequence of array elements within the array. See also Array.prototype.copyWithin().
TypedArray.prototype.entries()
Returns a new Array Iterator object that contains the key/value pairs for each index in the array. See also Array.prototype.entries().
TypedArray.prototype.every()
Tests whether all elements in the array pass the test provided by a function. See also Array.prototype.every().
TypedArray.prototype.fill()
Fills all the elements of an array from a start index to an end index with a static value. See also Array.prototype.fill().
TypedArray.prototype.filter()
Creates a new array with all of the elements of this array for which the provided filtering function returns true. See also Array.prototype.filter().
TypedArray.prototype.find()
Returns the found value in the array, if an element in the array satisfies the provided testing function, or undefined if not found. See also Array.prototype.find().
TypedArray.prototype.findIndex()
Returns the found index in the array, if an element in the array satisfies the provided testing function or -1 if not found. See also Array.prototype.findIndex().
TypedArray.prototype.forEach()
Calls a function for each element in the array. See also Array.prototype.forEach().
TypedArray.prototype.includes()
Determines whether a typed array includes a certain element, returning true or false as appropriate. See also Array.prototype.includes().
TypedArray.prototype.indexOf()
Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.indexOf().
TypedArray.prototype.join()
Joins all elements of an array into a string. See also Array.prototype.join().
TypedArray.prototype.keys()
Returns a new Array Iterator that contains the keys for each index in the array. See also Array.prototype.keys().
TypedArray.prototype.lastIndexOf()
Returns the last (greatest) index of an element within the array equal to the specified value, or -1 if none is found. See also Array.prototype.lastIndexOf().
TypedArray.prototype.map()
Creates a new array with the results of calling a provided function on every element in this array. See also Array.prototype.map().
TypedArray.prototype.reduce()
Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value. See also Array.prototype.reduce().
TypedArray.prototype.reduceRight()
Apply a function against an accumulator and each value of the array (from right-to-left) as to reduce it to a single value. See also Array.prototype.reduceRight().
TypedArray.prototype.reverse()
Reverses the order of the elements of an array — the first becomes the last, and the last becomes the first. See also Array.prototype.reverse().
TypedArray.prototype.set()
Stores multiple values in the typed array, reading input values from a specified array.
TypedArray.prototype.slice()
Extracts a section of an array and returns a new array. See also Array.prototype.slice().
TypedArray.prototype.some()
Returns true if at least one element in this array satisfies the provided testing function. See also Array.prototype.some().
TypedArray.prototype.sort()
Sorts the elements of an array in place and returns the array. See also Array.prototype.sort().
TypedArray.prototype.subarray()
Returns a new TypedArray from the given start and end element index.
TypedArray.prototype.values()
Returns a new Array Iterator object that contains the values for each index in the array. See also Array.prototype.values().
TypedArray.prototype.toLocaleString()
Returns a localized string representing the array and its elements. See also Array.prototype.toLocaleString().
TypedArray.prototype.toString()
Returns a string representing the array and its elements. See also Array.prototype.toString().
TypedArray.prototype[@@iterator]()
Returns a new Array Iterator object that contains the values for each index in the array.

Examples

New is required

Starting with ECMAScript 2015, TypedArray constructors must be constructed with the new operator. Calling a TypedArray constructor as a function without new will throw a TypeError.

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

Property access

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"

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
TypedArray 7 12 4 10 11.6 5.1
BYTES_PER_ELEMENT 7 12 4 10 11.6 5.1
buffer 7 14 4 10 11.6 5.1
byteLength 7 14 4 10 11.6 5.1
byteOffset 7 14 4 10 11.6 5.1
Constructor without arguments 7 12 55 10 11.6 5.1
copyWithin 45 14 34 No 36 9.1
entries 45 14 37 No 36 9.1
every 45 14 37 No 36 9.1
fill 45 14 37 No 36 9.1
filter 45 14 38 No No 9.1
find 45 14 37 No 32 9.1
findIndex 45 14 37 No 32 9.1
forEach 45 14 38 No 32 10
from 45 14 38 No No 10
includes 47 14 43 No 34 10
Indexed properties not consulting prototype 7
7
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
12
12
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
25 10
10
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
11.6
11.6
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
5.1
5.1
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
indexOf 45 14 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).indexOf(0, -0) will now always return +0.
No 32 9.1
Iterable in constructor 39 14 52 No 26 10
join 45 14 37 No 32 9.1
keys 38 14 37 No 25 10
lastIndexOf 45 14 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).lastIndexOf(0, -0) will now always return +0.
No 32 10
length 7 14 4 10 11.6 5.1
map 45 14 38 No 32 9.1
name 7 12 4 10 11.6 5.1
Named properties 7 12 30 10 11.6 5.1
TypedArray() without new throws 7 14 44 No 15 5.1
of 45 14 38 No No 9.1
reduce 45 14 37 No 32 10
reduceRight 45 14 37 No 32 10
reverse 45 14 37 No 32 10
set 7 14 4 10 11.6 5.1
slice 45 14 38 No 32 10
some 45 14 37 No 32 10
sort 45 14 46 No 32 10
subarray 7 14 4 10 11.6 5.1
toLocaleString 7 12 51 10 11.6 5.1
toString 7 12 51 10 11.6 5.1
values 38 14 37 No 25 10
@@iterator 38 12 36
36
27 — 36
A placeholder property named @@iterator is used.
Uses the non-standard name: @@iterator
17 — 27
A placeholder property named iterator is used.
Uses the non-standard name: iterator
No 25 10
@@species 51 13 48 No 38 10
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
TypedArray 4 18 4 12 4.2 1.0
BYTES_PER_ELEMENT 4 18 4 12 4.2 1.0
buffer 4 18 4 12 4.2 1.0
byteLength 4 18 4 12 4.2 1.0
byteOffset 4 18 4 12 4.2 1.0
Constructor without arguments ≤37 18 55 12 5 1.0
copyWithin No No 34 No 9.3 No
entries No 45 37 No 9.3 5.0
every No 45 37 No 9.3 5.0
fill No 45 37 No 9.3 5.0
filter No 45 38 No 9.3 5.0
find 45 45 37 32 9.3 5.0
findIndex 45 45 37 32 9.3 5.0
forEach 45 45 38 32 10 5.0
from No No 38 No 10 No
includes No 47 43 34 10 5.0
Indexed properties not consulting prototype ≤37
≤37
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
18
18
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
25 12
12
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
5
5
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
1.0
1.0
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
indexOf No 45 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).indexOf(0, -0) will now always return +0.
32 9.3 5.0
Iterable in constructor 39 39 52 26 10 4.0
join 45 45 37 32 9.3 5.0
keys 38 38 37 25 10 3.0
lastIndexOf 45 45 37
37
Starting with Firefox 47, this method will no longer return -0. For example, new Uint8Array([0]).lastIndexOf(0, -0) will now always return +0.
32 10 5.0
length 4 18 4 12 4.2 1.0
map 45 45 38 32 9.3 5.0
name 4 18 4 12 4.2 1.0
Named properties ≤37 18 30 12 5 1.0
TypedArray() without new throws ≤37 18 44 14 5 1.0
of No No 38 No 9.3 No
reduce 45 45 37 No 10 5.0
reduceRight 45 45 37 No 10 5.0
reverse 45 45 37 No 10 5.0
set 4 18 4 12 4.2 1.0
slice 45 45 38 32 10 5.0
some 45 45 37 No 10 5.0
sort 45 45 46 32 10 5.0
subarray 4 18 4 12 4.2 1.0
toLocaleString ≤37 18 51 12 5 1.0
toString ≤37 18 51 12 5 1.0
values 38 38 37 25 10 3.0
@@iterator 38 38 36
36
27 — 36
A placeholder property named @@iterator is used.
Uses the non-standard name: @@iterator
17 — 27
A placeholder property named iterator is used.
Uses the non-standard name: iterator
25 10 3.0
@@species 51 51 48 41 10 5.0
Server
Node.js
TypedArray 0.10
BYTES_PER_ELEMENT 0.10
buffer 0.10
byteLength 0.10
byteOffset 0.10
Constructor without arguments 0.10
copyWithin 4.0.0
entries 0.12
every 4.0.0
fill 4.0.0
filter 4.0.0
find 4.0.0
findIndex 4.0.0
forEach 4.0.0
from 4.0.0
includes 6.0.0
6.0.0
5.0.0
Disabled
Disabled From version 5.0.0: this feature is behind the --harmony runtime flag.
Indexed properties not consulting prototype 0.10
0.10
Negative integers are not considered as indexed properties and therefore return the value of the prototype property.
indexOf 4.0.0
Iterable in constructor 4.0.0
join 4.0.0
keys 0.12
lastIndexOf 4.0.0
length 0.10
map 4.0.0
name 0.10
Named properties 0.10
TypedArray() without new throws 0.12
of 4.0.0
reduce 4.0.0
reduceRight 4.0.0
reverse 4.0.0
set 0.10
slice 4.0.0
some 4.0.0
sort 4.0.0
subarray 0.12
toLocaleString 0.10
toString 0.10
values 0.12
@@iterator 0.12
@@species 6.5.0
6.5.0
6.0.0
Disabled
Disabled From version 6.0.0: this feature is behind the --harmony runtime flag.

See also

© 2005–2018 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://wiki.developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray