DataView.prototype.byteLength

## Description

The `byteLength` property is an accessor property whose set accessor function is `undefined`, meaning that you can only read this property. If the `DataView` is [length-tracking](/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray#behavior_when_viewing_a_resizable_buffer), then its length depends on the length of the underlying buffer, and may change if the buffer is resized. Otherwise, the value is established when the `DataView` is constructed and cannot be changed. Whether length-tracking or not, the `byteLength` becomes 0 if the underlying buffer is resized such that the viewed range is no longer valid.

## Examples

### Using the byteLength property

```js
const buffer = new ArrayBuffer(8);
const dataview = new DataView(buffer);
dataview.byteLength; // 8 (matches the byteLength of the buffer)

const dataview2 = new DataView(buffer, 1, 5);
dataview2.byteLength; // 5 (as specified when constructing the DataView)

const dataview3 = new DataView(buffer, 2);
dataview3.byteLength; // 6 (due to the offset of the constructed DataView)

const buffer2 = new ArrayBuffer(16, { maxByteLength: 32 });
const dataviewLengthTracking = new DataView(buffer2, 4);
dataviewLengthTracking.byteLength; // 12 (16 - 4)
buffer2.resize(20);
dataviewLengthTracking.byteLength; // 16 (20 - 4)
buffer2.resize(3);
dataviewLengthTracking.byteLength; // 0 (viewed range is no longer valid)