The getBigUint64() method of DataView instances reads 8 bytes starting at the specified byte offset of this DataView and interprets them as a 64-bit unsigned integer. There is no alignment constraint; multi-byte values may be fetched from any offset within bounds.

Try it

// Create an ArrayBuffer with a size in bytes
const buffer = new ArrayBuffer(16);

// Highest possible BigInt value that fits in an unsigned 64-bit integer
const max = 2n ** 64n - 1n;

const view = new DataView(buffer);
view.setBigUint64(1, max);

console.log(view.getBigUint64(1));
// Expected output: 18446744073709551615n

Syntax

getBigUint64(byteOffset)
getBigUint64(byteOffset, littleEndian)

Parameters

byteOffset

The offset, in bytes, from the start of the view to read the data from.

littleEndian Optional

Indicates whether the data is stored in little- or big-endian format. If false or undefined, a big-endian value is read.

Return value

A BigInt from 0 to 2⁶⁴-1, inclusive.

Exceptions

RangeError

Thrown if the byteOffset is set such that it would read beyond the end of the view.

Examples

Using getBigUint64()

const { buffer } = new Uint8Array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
const dataview = new DataView(buffer);
console.log(dataview.getBigUint64(1)); // 72623859790382856n

Specifications

Browser compatibility

See also

• JavaScript typed arrays guide
• DataView
• ArrayBuffer
• BigUint64Array