skills/docs/foundation/flow/streams/src/utils/buffer/buffer-to-uint8/buffer-to-uint8.md

bufferToUint8Array

(no submodules)

Purpose

bufferToUint8Array normalises the two byte-container shapes that show up in mixed Node/browser code — Buffer and ArrayBuffer — into the single canonical Uint8Array form used throughout @suaveplan/streams. The streams package treats Uint8Array as the universal byte chunk; this helper lets call sites accept either input without sprinkling instanceof checks across every adapter.

The conversion is zero-copy. For Buffer inputs we construct a view that respects the source's byteOffset / byteLength, which matters because Node typically slices new Buffers out of a shared pool. For ArrayBuffer inputs we wrap the entire buffer.

Features

• Accepts both Node Buffer and standard ArrayBuffer inputs.
• Zero-copy: never allocates a new backing buffer.
• Honours Buffer.subarray offsets correctly (avoids a common foot-gun).
• Pure synchronous function with no dependencies.

Usage: Basic Example

import { bufferToUint8Array } from "@suaveplan/streams/utils/buffer/buffer-to-uint8/buffer-to-uint8";

const u8 = bufferToUint8Array(Buffer.from("hello"));
console.log(u8.byteLength); // 5

Usage: Advanced Example

import { bufferToUint8Array } from "@suaveplan/streams/utils/buffer/buffer-to-uint8/buffer-to-uint8";

// Coming from `node:fs/promises#readFile` (returns Buffer in Node)
async function loadAsU8(path: string): Promise<Uint8Array> {
    const { readFile } = await import("node:fs/promises");
    return bufferToUint8Array(await readFile(path));
}

// Coming from a browser `Response.arrayBuffer()`
async function fetchAsU8(url: string): Promise<Uint8Array> {
    const ab = await (await fetch(url)).arrayBuffer();
    return bufferToUint8Array(ab);
}

API Reference

bufferToUint8Array(buffer: Buffer | ArrayBuffer): Uint8Array

• buffer — either a Node Buffer (a Uint8Array subclass with possibly non-zero byteOffset) or a standard DOM/ES ArrayBuffer.
• Returns — a Uint8Array view over the same memory as the input.
• Throws — never; type narrowing is performed via instanceof ArrayBuffer.

Implementation Notes

• The instanceof ArrayBuffer check intentionally precedes the Buffer branch because Buffer instanceof ArrayBuffer is false in Node (Buffer extends Uint8Array, not ArrayBuffer).
• The returned view shares memory with the source. If you need an independent copy, follow up with .slice() or pair this helper with createUint8ArraySlice.
• Universal: this module has no Node-only or DOM-only imports.