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).


new Int8Array(); // new in ES2017
new Int8Array(length);
new Int8Array(typedArray);
new Int8Array(object);
new Int8Array(buffer [, byteOffset [, 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.
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.
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.


Different ways to create an Int8Array

// From a length
var 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
var arr = new Int8Array([21,31]);
console.log(arr[1]); // 31

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

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

// From an iterable
var iterable = function*(){ yield* [1,2,3]; }();
var int8 = new Int8Array(iterable);
// Int8Array[1, 2, 3]


Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Int8Array() constructor 7 12 4 10 11.6 5.1
Constructor without arguments 7 12 55 10 11.6 5.1
new Int8Array(iterable) 39 14 52 No 26 10
Int8Array() without new throws 7 14 44 No 15 5.1
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
Int8Array() constructor 4 18 4 12 4.2 1.0
Constructor without arguments ≤37 18 55 12 5 1.0
new Int8Array(iterable) 39 39 52 26 10 4.0
Int8Array() without new throws ≤37 18 44 14 5 1.0
Int8Array() constructor 0.10
Constructor without arguments 0.10
new Int8Array(iterable) 4.0.0
Int8Array() without new throws 0.12

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.

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

See also

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