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# DataView.prototype.getBigUint64()

The **`getBigUint64()`** method gets an unsigned 64-bit integer
(unsigned long long) at the specified byte offset from the start of the
[`DataView`](../../../globals/DataView/DataView.mdx).

## Syntax

```js
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 64-bit int is stored in [little- or big-endian](https://developer.mozilla.org/docs/Glossary/Endianness) format. If
    `false` or `undefined`, a big-endian value is read.

### Return value

A `BigInt`.

### Errors thrown

- [`RangeError`](../../RangeError/RangeError.mdx)
  - : Thrown if the `byteOffset` is set such that it would read beyond the end
    of the view.

## Description

There is no alignment constraint; multi-byte values may be fetched from any offset.
