静态方法:Buffer.from(arrayBuffer[, byteOffset[, length]])

\Static method: Buffer.from(arrayBuffer[, byteOffset[, length]])

• arrayBuffer <ArrayBuffer> | <SharedArrayBuffer> <ArrayBuffer>、<SharedArrayBuffer>,例如 <TypedArray> 的 .buffer 属性。

  \arrayBuffer <ArrayBuffer> | <SharedArrayBuffer> An <ArrayBuffer>, <SharedArrayBuffer>, for example the .buffer property of a <TypedArray>.

• byteOffset <integer> 要暴露的第一个字节的索引。默认值:0。

  \byteOffset <integer> Index of first byte to expose. Default: 0.

• length <integer> 要暴露的字节数。默认值:arrayBuffer.byteLength - byteOffset。

  \length <integer> Number of bytes to expose. Default: arrayBuffer.byteLength - byteOffset.

• 返回:<Buffer>

  \Returns: <Buffer>

这将创建 <ArrayBuffer> 的视图,而无需复制底层内存。例如,当传入对 <TypedArray> 实例的 .buffer 属性的引用时,新创建的 Buffer 将与 <TypedArray> 的底层 ArrayBuffer 共享相同的分配内存。

\This creates a view of the <ArrayBuffer> without copying the underlying memory. For example, when passed a reference to the .buffer property of a <TypedArray> instance, the newly created Buffer will share the same allocated memory as the <TypedArray>'s underlying ArrayBuffer.

import { Buffer } from 'node:buffer';
const arr = new Uint16Array(2);
arr[0] = 5000;
arr[1] = 4000;
// Shares memory with `arr`.
const buf = Buffer.from(arr.buffer);
console.log(buf);
// Prints: <Buffer 88 13 a0 0f>
// Changing the original Uint16Array changes the Buffer also.
arr[1] = 6000;
console.log(buf);
// Prints: <Buffer 88 13 70 17>const { Buffer } = require('node:buffer');
const arr = new Uint16Array(2);
arr[0] = 5000;
arr[1] = 4000;
// Shares memory with `arr`.
const buf = Buffer.from(arr.buffer);
console.log(buf);
// Prints: <Buffer 88 13 a0 0f>
// Changing the original Uint16Array changes the Buffer also.
arr[1] = 6000;
console.log(buf);
// Prints: <Buffer 88 13 70 17>拷贝

可选的 byteOffset 和 length 参数指定了 arrayBuffer 中将由 Buffer 共享的内存范围。

\The optional byteOffset and length arguments specify a memory range within the arrayBuffer that will be shared by the Buffer.

import { Buffer } from 'node:buffer';
const ab = new ArrayBuffer(10);
const buf = Buffer.from(ab, 0, 2);
console.log(buf.length);
// Prints: 2const { Buffer } = require('node:buffer');
const ab = new ArrayBuffer(10);
const buf = Buffer.from(ab, 0, 2);
console.log(buf.length);
// Prints: 2拷贝

如果 arrayBuffer 不是 <ArrayBuffer> 或 <SharedArrayBuffer> 或其他适用于 Buffer.from() 变体的类型,则将抛出 TypeError。

\A TypeError will be thrown if arrayBuffer is not an <ArrayBuffer> or a <SharedArrayBuffer> or another type appropriate for Buffer.from() variants.

记住,支持 ArrayBuffer 可以覆盖超出 TypedArray 视图边界的内存范围。使用 TypedArray 的 buffer 属性创建的新 Buffer 可能会超出 TypedArray 的范围:

\It is important to remember that a backing ArrayBuffer can cover a range of memory that extends beyond the bounds of a TypedArray view. A new Buffer created using the buffer property of a TypedArray may extend beyond the range of the TypedArray:

import { Buffer } from 'node:buffer';
const arrA = Uint8Array.from([0x63, 0x64, 0x65, 0x66]); // 4 elements
const arrB = new Uint8Array(arrA.buffer, 1, 2); // 2 elements
console.log(arrA.buffer === arrB.buffer); // true
const buf = Buffer.from(arrB.buffer);
console.log(buf);
// Prints: <Buffer 63 64 65 66>const { Buffer } = require('node:buffer');
const arrA = Uint8Array.from([0x63, 0x64, 0x65, 0x66]); // 4 elements
const arrB = new Uint8Array(arrA.buffer, 1, 2); // 2 elements
console.log(arrA.buffer === arrB.buffer); // true
const buf = Buffer.from(arrB.buffer);
console.log(buf);
// Prints: <Buffer 63 64 65 66>拷贝