---
title: BigInt64Array
slug: Web/JavaScript/Reference/Global_Objects/BigInt64Array
page-type: javascript-class
browser-compat: javascript.builtins.BigInt64Array
sidebar: jsref
---

The **`BigInt64Array`** typed array represents an array of 64-bit signed integers in the platform byte order. If control over byte order is needed, use {{jsxref("DataView")}} instead. The contents are initialized to `0n` unless initialization data is explicitly provided. 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).

`BigInt64Array` is a subclass of the hidden {{jsxref("TypedArray")}} class.

{{InteractiveExample("JavaScript Demo: BigInt64Array", "taller")}}

```js interactive-example
const buffer = new ArrayBuffer(24);
const bigint64 = new BigInt64Array(buffer);
bigint64[0] = 5886014448488689n;
bigint64[1] = 1881938909131133n;
bigint64[2] = 1898875537769492n;

bigint64[0] = 6118793953620967n;
console.log(bigint64);
// Expected Output: BigInt64Array [6118793953620967n, 1881938909131133n, 1898875537769492n]

console.log(bigint64[2]);
// Expected Output: 1898875537769492n

console.log("Array length:", bigint64.length);
// Expected Output: Array length: 3

console.log("Array byte length:", bigint64.byteLength);
// Expected Output: Array byte length: 24

console.log("Array byte offset:", bigint64.byteOffset);
// Expected Output: Array byte offset: 0

bigint64.set([100n, 200n], 1);
console.log(bigint64);
// Expected Output: BigInt64Array [6118793953620967n, 100n, 200n]
```

## Constructor

- {{jsxref("BigInt64Array/BigInt64Array", "BigInt64Array()")}}
  - : Creates a new `BigInt64Array` object.

## Static properties

_Also inherits static properties from its parent {{jsxref("TypedArray")}}_.

- {{jsxref("TypedArray/BYTES_PER_ELEMENT", "BigInt64Array.BYTES_PER_ELEMENT")}}
  - : Returns a number value of the element size. `8` in the case of `BigInt64Array`.

## Static methods

_Inherits static methods from its parent {{jsxref("TypedArray")}}_.

## Instance properties

_Also inherits instance properties from its parent {{jsxref("TypedArray")}}_.

These properties are defined on `BigInt64Array.prototype` and shared by all `BigInt64Array` instances.

- {{jsxref("TypedArray/BYTES_PER_ELEMENT", "BigInt64Array.prototype.BYTES_PER_ELEMENT")}}
  - : Returns a number value of the element size. `8` in the case of a `BigInt64Array`.
- {{jsxref("Object/constructor", "BigInt64Array.prototype.constructor")}}
  - : The constructor function that created the instance object. For `BigInt64Array` instances, the initial value is the {{jsxref("BigInt64Array/BigInt64Array", "BigInt64Array")}} constructor.

## Instance methods

_Inherits instance methods from its parent {{jsxref("TypedArray")}}_.

## Examples

### Different ways to create a BigInt64Array

```js
// From a length
const bigint64 = new BigInt64Array(2);
bigint64[0] = 42n;
console.log(bigint64[0]); // 42n
console.log(bigint64.length); // 2
console.log(bigint64.BYTES_PER_ELEMENT); // 8

// From an array
const x = new BigInt64Array([21n, 31n]);
console.log(x[1]); // 31n

// From another TypedArray
const y = new BigInt64Array(x);
console.log(y[0]); // 21n

// From an ArrayBuffer
const buffer = new ArrayBuffer(64);
const z = new BigInt64Array(buffer, 8, 4);
console.log(z.byteOffset); // 8

// From an iterable
const iterable = (function* () {
  yield* [1n, 2n, 3n];
})();
const bigint64FromIterable = new BigInt64Array(iterable);
console.log(bigint64FromIterable);
// BigInt64Array [1n, 2n, 3n]
```

## Specifications

{{Specifications}}

## Browser compatibility

{{Compat}}

## See also

- [JavaScript typed arrays](/en-US/docs/Web/JavaScript/Guide/Typed_arrays) guide
- {{jsxref("TypedArray")}}
- {{jsxref("ArrayBuffer")}}
- {{jsxref("DataView")}}