buf.byteOffset

• <integer> Buffer 底层 ArrayBuffer 对象的 byteOffset。

当在 Buffer.from(ArrayBuffer, byteOffset, length) 中设置 byteOffset 时，或者有时在分配小于 Buffer.poolSize 的 Buffer 时，缓冲区不会从底层 ArrayBuffer 上的零偏移量开始。

这在使用 buf.buffer 直接访问底层 ArrayBuffer 时可能会导致问题，因为 ArrayBuffer 的其他部分可能与 Buffer 对象本身无关。

创建与 Buffer 共享内存的 TypedArray 对象时的常见问题是，在这种情况下，需要正确指定 byteOffset：

import { Buffer } from 'node:buffer';

// 创建小于 `Buffer.poolSize` 的缓冲区。
const nodeBuffer = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

// 当将 Node.js 缓冲区转换为 Int8Array 时，
// 使用 byteOffset 仅引用包含 `nodeBuffer` 内存的 `nodeBuffer.buffer` 部分。
new Int8Array(nodeBuffer.buffer, nodeBuffer.byteOffset, nodeBuffer.length);const { Buffer } = require('node:buffer');

// 创建小于 `Buffer.poolSize` 的缓冲区。
const nodeBuffer = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

// 当将 Node.js 缓冲区转换为 Int8Array 时，
// 使用 byteOffset 仅引用包含 `nodeBuffer` 内存的 `nodeBuffer.buffer` 部分。
new Int8Array(nodeBuffer.buffer, nodeBuffer.byteOffset, nodeBuffer.length);

• <integer> The byteOffset of the Buffers underlying ArrayBuffer object.

When setting byteOffset in Buffer.from(ArrayBuffer, byteOffset, length), or sometimes when allocating a Buffer smaller than Buffer.poolSize, the buffer does not start from a zero offset on the underlying ArrayBuffer.

This can cause problems when accessing the underlying ArrayBuffer directly using buf.buffer, as other parts of the ArrayBuffer may be unrelated to the Buffer object itself.

A common issue when creating a TypedArray object that shares its memory with a Buffer is that in this case one needs to specify the byteOffset correctly:

import { Buffer } from 'node:buffer';

// Create a buffer smaller than `Buffer.poolSize`.
const nodeBuffer = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

// When casting the Node.js Buffer to an Int8Array, use the byteOffset
// to refer only to the part of `nodeBuffer.buffer` that contains the memory
// for `nodeBuffer`.
new Int8Array(nodeBuffer.buffer, nodeBuffer.byteOffset, nodeBuffer.length);const { Buffer } = require('node:buffer');

// Create a buffer smaller than `Buffer.poolSize`.
const nodeBuffer = Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);

// When casting the Node.js Buffer to an Int8Array, use the byteOffset
// to refer only to the part of `nodeBuffer.buffer` that contains the memory
// for `nodeBuffer`.
new Int8Array(nodeBuffer.buffer, nodeBuffer.byteOffset, nodeBuffer.length);