Int8Array() constructor

The Int8Array() constructor creates a typed array of twos-complement 8-bit signed integers. The contents are initialized to 0. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation).

Syntax

new Int8Array(); // new in ES2017
new Int8Array(length);
new Int8Array(typedArray);
new Int8Array(object);

new Int8Array(buffer);
new Int8Array(buffer, byteOffset);
new Int8Array(buffer, byteOffset, length);

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 non-bigint 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.

Examples

Different ways to create an Int8Array

// From a length
const int8 = new Int8Array(2);
int8[0] = 42;
console.log(int8[0]); // 42
console.log(int8.length); // 2
console.log(int8.BYTES_PER_ELEMENT); // 1

// From an array
const arr = new Int8Array([21,31]);
console.log(arr[1]); // 31

// From another TypedArray
const x = new Int8Array([21, 31]);
const y = new Int8Array(x);
console.log(y[0]); // 21

// From an ArrayBuffer
const buffer = new ArrayBuffer(8);
const z = new Int8Array(buffer, 1, 4);

// From an iterable
const iterable = function*(){ yield* [1,2,3]; }();
const int8_from_iterable = new Int8Array(iterable);
// Int8Array[1, 2, 3]

Specifications

Specification
ECMAScript Language Specification
# sec-typedarray-constructors

Browser compatibility

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Compatibility notes

Starting with ECMAScript 2015, Int8Array constructors require to be constructed with a new operator. Calling a Int8Array constructor as a function without new, will throw a TypeError from now on. 

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

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

See also