GeezerVison

A Uint8Array is a typed array, a view over data in an underlying ArrayBuffer. The buffer property returns that ArrayBuffer.

const arr = new Uint8Array(64);
arr.buffer; // => ArrayBuffer(64)

The Uint8Array may be a view over a subset of the data in the underlying ArrayBuffer. In this case, the buffer property returns the entire buffer, and the byteOffset and byteLength properties indicate the subset.

const arr = new Uint8Array(new ArrayBuffer(64), 16, 32);
arr.buffer; // => ArrayBuffer(64)
arr.byteOffset; // => 16
arr.byteLength; // => 32

See Binary Data.