Bun provides a number of convenience functions for reading the contents of a ReadableStream into different formats. This snippet reads the contents of a ReadableStream to an ArrayBuffer, then creates a Uint8Array that points to the buffer.
const stream = new ReadableStream();
const buf = await Bun.readableStreamToArrayBuffer(stream);
const uint8 = new Uint8Array(buf);
Additionally, there is a convenience method to convert to Uint8Array directly.
const stream = new ReadableStream();
const uint8 = await Bun.readableStreamToBytes(stream);
See Docs > API > Utils for documentation on Bun's other ReadableStream conversion functions.