files/en-us/web/javascript/reference/global_objects/biguint64array/index.md
The BigUint64Array typed array represents an array of 64-bit unsigned 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).
BigUint64Array is a subclass of the hidden {{jsxref("TypedArray")}} class.
BigUint64Array object.Also inherits static properties from its parent {{jsxref("TypedArray")}}.
8 in the case of BigUint64Array.Inherits static methods from its parent {{jsxref("TypedArray")}}.
Also inherits instance properties from its parent {{jsxref("TypedArray")}}.
These properties are defined on BigUint64Array.prototype and shared by all BigUint64Array instances.
8 in the case of a BigUint64Array.BigUint64Array instances, the initial value is the {{jsxref("BigUint64Array/BigUint64Array", "BigUint64Array")}} constructor.Inherits instance methods from its parent {{jsxref("TypedArray")}}.
// From a length
const biguint64 = new BigUint64Array(2);
biguint64[0] = 42n;
console.log(biguint64[0]); // 42n
console.log(biguint64.length); // 2
console.log(biguint64.BYTES_PER_ELEMENT); // 8
// From an array
const x = new BigUint64Array([21n, 31n]);
console.log(x[1]); // 31n
// From another TypedArray
const y = new BigUint64Array(x);
console.log(y[0]); // 21n
// From an ArrayBuffer
const buffer = new ArrayBuffer(64);
const z = new BigUint64Array(buffer, 8, 4);
console.log(z.byteOffset); // 8
// From an iterable
const iterable = (function* () {
yield* [1n, 2n, 3n];
})();
const biguint64FromIterable = new BigUint64Array(iterable);
console.log(biguint64FromIterable);
// BigUint64Array [1n, 2n, 3n]
{{Specifications}}
{{Compat}}