DataView.prototype.getBigUint64()

// 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

getBigUint64(byteOffset);
getBigUint64(byteOffset, littleEndian);

var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.getBigUint64(0); // 0n