Node.js v20.11.0 文档


缓冲区#

Buffer

稳定性: 2 - 稳定的

Stability: 2 - Stable

源代码: lib/buffer.js

Buffer 对象用于表示固定长度的字节序列。许多 Node.js API 都支持 Buffer

Buffer objects are used to represent a fixed-length sequence of bytes. Many Node.js APIs support Buffers.

Buffer 类是 JavaScript Uint8Array 类的子类,并使用涵盖额外用例的方法对其进行扩展。Node.js API 在支持 Buffer 的地方也接受纯 Uint8Array

The Buffer class is a subclass of JavaScript's Uint8Array class and extends it with methods that cover additional use cases. Node.js APIs accept plain Uint8Arrays wherever Buffers are supported as well.

虽然 Buffer 类在全局作用域内可用,但仍然建议通过 import 或 require 语句显式地引用它。

While the Buffer class is available within the global scope, it is still recommended to explicitly reference it via an import or require statement.

import { Buffer } from 'node:buffer';

// Creates a zero-filled Buffer of length 10.
const buf1 = Buffer.alloc(10);

// Creates a Buffer of length 10,
// filled with bytes which all have the value `1`.
const buf2 = Buffer.alloc(10, 1);

// Creates an uninitialized buffer of length 10.
// This is faster than calling Buffer.alloc() but the returned
// Buffer instance might contain old data that needs to be
// overwritten using fill(), write(), or other functions that fill the Buffer's
// contents.
const buf3 = Buffer.allocUnsafe(10);

// Creates a Buffer containing the bytes [1, 2, 3].
const buf4 = Buffer.from([1, 2, 3]);

// Creates a Buffer containing the bytes [1, 1, 1, 1] – the entries
// are all truncated using `(value & 255)` to fit into the range 0–255.
const buf5 = Buffer.from([257, 257.5, -255, '1']);

// Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést':
// [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation)
// [116, 195, 169, 115, 116] (in decimal notation)
const buf6 = Buffer.from('tést');

// Creates a Buffer containing the Latin-1 bytes [0x74, 0xe9, 0x73, 0x74].
const buf7 = Buffer.from('tést', 'latin1');const { Buffer } = require('node:buffer');

// Creates a zero-filled Buffer of length 10.
const buf1 = Buffer.alloc(10);

// Creates a Buffer of length 10,
// filled with bytes which all have the value `1`.
const buf2 = Buffer.alloc(10, 1);

// Creates an uninitialized buffer of length 10.
// This is faster than calling Buffer.alloc() but the returned
// Buffer instance might contain old data that needs to be
// overwritten using fill(), write(), or other functions that fill the Buffer's
// contents.
const buf3 = Buffer.allocUnsafe(10);

// Creates a Buffer containing the bytes [1, 2, 3].
const buf4 = Buffer.from([1, 2, 3]);

// Creates a Buffer containing the bytes [1, 1, 1, 1] – the entries
// are all truncated using `(value & 255)` to fit into the range 0–255.
const buf5 = Buffer.from([257, 257.5, -255, '1']);

// Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést':
// [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation)
// [116, 195, 169, 115, 116] (in decimal notation)
const buf6 = Buffer.from('tést');

// Creates a Buffer containing the Latin-1 bytes [0x74, 0xe9, 0x73, 0x74].
const buf7 = Buffer.from('tést', 'latin1');

缓冲区和字符编码#

Buffers and character encodings

Buffer 和字符串之间转换时,可以指定字符编码。如果未指定字符编码,则默认使用 UTF-8。

When converting between Buffers and strings, a character encoding may be specified. If no character encoding is specified, UTF-8 will be used as the default.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('hello world', 'utf8');

console.log(buf.toString('hex'));
// Prints: 68656c6c6f20776f726c64
console.log(buf.toString('base64'));
// Prints: aGVsbG8gd29ybGQ=

console.log(Buffer.from('fhqwhgads', 'utf8'));
// Prints: <Buffer 66 68 71 77 68 67 61 64 73>
console.log(Buffer.from('fhqwhgads', 'utf16le'));
// Prints: <Buffer 66 00 68 00 71 00 77 00 68 00 67 00 61 00 64 00 73 00>const { Buffer } = require('node:buffer');

const buf = Buffer.from('hello world', 'utf8');

console.log(buf.toString('hex'));
// Prints: 68656c6c6f20776f726c64
console.log(buf.toString('base64'));
// Prints: aGVsbG8gd29ybGQ=

console.log(Buffer.from('fhqwhgads', 'utf8'));
// Prints: <Buffer 66 68 71 77 68 67 61 64 73>
console.log(Buffer.from('fhqwhgads', 'utf16le'));
// Prints: <Buffer 66 00 68 00 71 00 77 00 68 00 67 00 61 00 64 00 73 00>

Node.js 缓冲区接受它们接收到的编码字符串的所有大小写变体。例如,UTF-8 可以指定为 'utf8''UTF8''uTf8'

Node.js buffers accept all case variations of encoding strings that they receive. For example, UTF-8 can be specified as 'utf8', 'UTF8', or 'uTf8'.

Node.js 目前支持的字符编码如下:

The character encodings currently supported by Node.js are the following:

  • 'utf8'(别名:'utf-8'):多字节编码的 Unicode 字符。许多网页和其他文档格式都使用 UTF-8。这是默认的字符编码。将 Buffer 解码为不专门包含有效 UTF-8 数据的字符串时,Unicode 替换字符 U+FFFD � 将用于表示这些错误。

    'utf8' (alias: 'utf-8'): Multi-byte encoded Unicode characters. Many web pages and other document formats use UTF-8. This is the default character encoding. When decoding a Buffer into a string that does not exclusively contain valid UTF-8 data, the Unicode replacement character U+FFFD � will be used to represent those errors.

  • 'utf16le'(别名:'utf-16le'):多字节编码的 Unicode 字符。与 'utf8' 不同,字符串中的每个字符都将使用 2 或 4 个字节进行编码。Node.js 仅支持 UTF-16little-endian 变体。

    'utf16le' (alias: 'utf-16le'): Multi-byte encoded Unicode characters. Unlike 'utf8', each character in the string will be encoded using either 2 or 4 bytes. Node.js only supports the little-endian variant of UTF-16.

  • 'latin1':Latin-1 代表 ISO-8859-1。此字符编码仅支持 U+0000U+00FF 的 Unicode 字符。每个字符都使用单个字节进行编码。不符合该范围的字符将被截断并映射到该范围内的字符。

    'latin1': Latin-1 stands for ISO-8859-1. This character encoding only supports the Unicode characters from U+0000 to U+00FF. Each character is encoded using a single byte. Characters that do not fit into that range are truncated and will be mapped to characters in that range.

使用以上编码之一将 Buffer 转换为字符串称为解码,将字符串转换为 Buffer 称为编码。

Converting a Buffer into a string using one of the above is referred to as decoding, and converting a string into a Buffer is referred to as encoding.

Node.js 还支持以下二进制转文本的编码。对于二进制到文本的编码,命名约定是相反的:将 Buffer 转换为字符串通常称为编码,将字符串转换为 Buffer 称为解码。

Node.js also supports the following binary-to-text encodings. For binary-to-text encodings, the naming convention is reversed: Converting a Buffer into a string is typically referred to as encoding, and converting a string into a Buffer as decoding.

  • 'base64'Base64 编码。从字符串创建 Buffer 时,此编码也将正确接受 RFC 4648,第 5 节 中指定的 "URL 和文件名安全字母表"。base64 编码的字符串中包含的空白字符(例如空格、制表符和换行符)会被忽略。

    'base64': Base64 encoding. When creating a Buffer from a string, this encoding will also correctly accept "URL and Filename Safe Alphabet" as specified in RFC 4648, Section 5. Whitespace characters such as spaces, tabs, and new lines contained within the base64-encoded string are ignored.

  • 'base64url'RFC 4648,第 5 节 中指定的 base64url 编码。当从字符串创建 Buffer 时,此编码也将正确接受常规的 base64 编码的字符串。当将 Buffer 编码为字符串时,此编码将忽略填充。

    'base64url': base64url encoding as specified in RFC 4648, Section 5. When creating a Buffer from a string, this encoding will also correctly accept regular base64-encoded strings. When encoding a Buffer to a string, this encoding will omit padding.

  • 'hex':将每个字节编码为两个十六进制字符。当解码不完全由偶数个十六进制字符组成的字符串时,可能会发生数据截断。请参阅下面的示例。

    'hex': Encode each byte as two hexadecimal characters. Data truncation may occur when decoding strings that do not exclusively consist of an even number of hexadecimal characters. See below for an example.

还支持以下旧版字符编码:

The following legacy character encodings are also supported:

  • 'ascii':仅适用于 7 位 ASCII 数据。当将字符串编码为 Buffer 时,这等效于使用 'latin1'。当将 Buffer 解码为字符串时,使用此编码将在解码为 'latin1' 之前额外取消设置每个字节的最高位。通常,没有理由使用此编码,因为在编码或解码纯 ASCII 文本时,'utf8'(或者,如果已知数据始终是纯 ASCII,则为 'latin1')将是更好的选择。它仅用于旧版兼容性。

    'ascii': For 7-bit ASCII data only. When encoding a string into a Buffer, this is equivalent to using 'latin1'. When decoding a Buffer into a string, using this encoding will additionally unset the highest bit of each byte before decoding as 'latin1'. Generally, there should be no reason to use this encoding, as 'utf8' (or, if the data is known to always be ASCII-only, 'latin1') will be a better choice when encoding or decoding ASCII-only text. It is only provided for legacy compatibility.

  • 'binary''latin1' 的别名。此编码的名称很容易让人误解,因为这里列出的所有编码都在字符串和二进制数据之间进行转换。对于字符串和 Buffer 之间的转换,通常 'utf8' 是正确的选择。

    'binary': Alias for 'latin1'. The name of this encoding can be very misleading, as all of the encodings listed here convert between strings and binary data. For converting between strings and Buffers, typically 'utf8' is the right choice.

  • 'ucs2', 'ucs-2':'utf16le' 的别名。UCS-2 过去指的是 UTF-16 的一种变体,它不支持代码点大于 U+FFFF 的字符。在 Node.js 中,始终支持这些代码点。

    'ucs2', 'ucs-2': Aliases of 'utf16le'. UCS-2 used to refer to a variant of UTF-16 that did not support characters that had code points larger than U+FFFF. In Node.js, these code points are always supported.

import { Buffer } from 'node:buffer';

Buffer.from('1ag123', 'hex');
// Prints <Buffer 1a>, data truncated when first non-hexadecimal value
// ('g') encountered.

Buffer.from('1a7', 'hex');
// Prints <Buffer 1a>, data truncated when data ends in single digit ('7').

Buffer.from('1634', 'hex');
// Prints <Buffer 16 34>, all data represented.const { Buffer } = require('node:buffer');

Buffer.from('1ag123', 'hex');
// Prints <Buffer 1a>, data truncated when first non-hexadecimal value
// ('g') encountered.

Buffer.from('1a7', 'hex');
// Prints <Buffer 1a>, data truncated when data ends in single digit ('7').

Buffer.from('1634', 'hex');
// Prints <Buffer 16 34>, all data represented.

现代 Web 浏览器遵循 WHATWG 编码标准,它将 'latin1''ISO-8859-1' 别名为 'win-1252'。这意味着在执行 http.get() 之类的操作时,如果返回的字符集是 WHATWG 规范中列出的字符集之一,则服务器实际上可能返回 'win-1252' 编码的数据,使用 'latin1' 编码可能会错误地解码字符。

Modern Web browsers follow the WHATWG Encoding Standard which aliases both 'latin1' and 'ISO-8859-1' to 'win-1252'. This means that while doing something like http.get(), if the returned charset is one of those listed in the WHATWG specification it is possible that the server actually returned 'win-1252'-encoded data, and using 'latin1' encoding may incorrectly decode the characters.

缓冲区和 TypedArray#

Buffers and TypedArrays

Buffer 实例也是 JavaScript Uint8ArrayTypedArray 实例。所有 TypedArray 方法都可用于 Buffer。但是,Buffer API 和 TypedArray API 之间存在细微的不兼容。

Buffer instances are also JavaScript Uint8Array and TypedArray instances. All TypedArray methods are available on Buffers. There are, however, subtle incompatibilities between the Buffer API and the TypedArray API.

特别是:

In particular:

有两种方式可以从 Buffer 创建新的 TypedArray 实例:

There are two ways to create new TypedArray instances from a Buffer:

  • Buffer 传递给 TypedArray 构造函数将复制 Buffer 内容,解释为整数数组,而不是目标类型的字节序列。

    Passing a Buffer to a TypedArray constructor will copy the Buffers contents, interpreted as an array of integers, and not as a byte sequence of the target type.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3, 4]);
const uint32array = new Uint32Array(buf);

console.log(uint32array);

// Prints: Uint32Array(4) [ 1, 2, 3, 4 ]const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3, 4]);
const uint32array = new Uint32Array(buf);

console.log(uint32array);

// Prints: Uint32Array(4) [ 1, 2, 3, 4 ]
import { Buffer } from 'node:buffer';

const buf = Buffer.from('hello', 'utf16le');
const uint16array = new Uint16Array(
  buf.buffer,
  buf.byteOffset,
  buf.length / Uint16Array.BYTES_PER_ELEMENT);

console.log(uint16array);

// Prints: Uint16Array(5) [ 104, 101, 108, 108, 111 ]const { Buffer } = require('node:buffer');

const buf = Buffer.from('hello', 'utf16le');
const uint16array = new Uint16Array(
  buf.buffer,
  buf.byteOffset,
  buf.length / Uint16Array.BYTES_PER_ELEMENT);

console.log(uint16array);

// Prints: Uint16Array(5) [ 104, 101, 108, 108, 111 ]

通过以相同的方式使用 TypedArray 对象的 .buffer 属性,可以创建与 TypedArray 实例共享相同分配内存的新 BufferBuffer.from() 在这种情况下表现得像 new Uint8Array()

It is possible to create a new Buffer that shares the same allocated memory as a TypedArray instance by using the TypedArray object's .buffer property in the same way. Buffer.from() behaves like new Uint8Array() in this context.

import { Buffer } from 'node:buffer';

const arr = new Uint16Array(2);

arr[0] = 5000;
arr[1] = 4000;

// Copies the contents of `arr`.
const buf1 = Buffer.from(arr);

// Shares memory with `arr`.
const buf2 = Buffer.from(arr.buffer);

console.log(buf1);
// Prints: <Buffer 88 a0>
console.log(buf2);
// Prints: <Buffer 88 13 a0 0f>

arr[1] = 6000;

console.log(buf1);
// Prints: <Buffer 88 a0>
console.log(buf2);
// Prints: <Buffer 88 13 70 17>const { Buffer } = require('node:buffer');

const arr = new Uint16Array(2);

arr[0] = 5000;
arr[1] = 4000;

// Copies the contents of `arr`.
const buf1 = Buffer.from(arr);

// Shares memory with `arr`.
const buf2 = Buffer.from(arr.buffer);

console.log(buf1);
// Prints: <Buffer 88 a0>
console.log(buf2);
// Prints: <Buffer 88 13 a0 0f>

arr[1] = 6000;

console.log(buf1);
// Prints: <Buffer 88 a0>
console.log(buf2);
// Prints: <Buffer 88 13 70 17>

使用 TypedArray.buffer 创建 Buffer 时,可以通过传入 byteOffsetlength 参数仅使用底层 ArrayBuffer 的一部分。

When creating a Buffer using a TypedArray's .buffer, it is possible to use only a portion of the underlying ArrayBuffer by passing in byteOffset and length parameters.

import { Buffer } from 'node:buffer';

const arr = new Uint16Array(20);
const buf = Buffer.from(arr.buffer, 0, 16);

console.log(buf.length);
// Prints: 16const { Buffer } = require('node:buffer');

const arr = new Uint16Array(20);
const buf = Buffer.from(arr.buffer, 0, 16);

console.log(buf.length);
// Prints: 16

Buffer.from()TypedArray.from() 具有不同的签名和实现。具体来说,TypedArray 变体接受第二个参数,该参数是在类型化数组的每个元素上调用的映射函数:

The Buffer.from() and TypedArray.from() have different signatures and implementations. Specifically, the TypedArray variants accept a second argument that is a mapping function that is invoked on every element of the typed array:

  • TypedArray.from(source[, mapFn[, thisArg]])

但是,Buffer.from() 方法不支持使用映射函数:

The Buffer.from() method, however, does not support the use of a mapping function:

缓冲区和迭代#

Buffers and iteration

可以使用 for..of 语法迭代 Buffer 实例:

Buffer instances can be iterated over using for..of syntax:

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3]);

for (const b of buf) {
  console.log(b);
}
// Prints:
//   1
//   2
//   3const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3]);

for (const b of buf) {
  console.log(b);
}
// Prints:
//   1
//   2
//   3

此外,buf.values()buf.keys()buf.entries() 方法可用于创建迭代器。

Additionally, the buf.values(), buf.keys(), and buf.entries() methods can be used to create iterators.

类:Blob#

Class: Blob

Blob 封装了不可变的原始数据,可以在多个工作线程之间安全地共享。

A Blob encapsulates immutable, raw data that can be safely shared across multiple worker threads.

new buffer.Blob([sources[, options]])#

创建新的 Blob 对象,其中包含给定源的串接。

Creates a new Blob object containing a concatenation of the given sources.

<ArrayBuffer><TypedArray><DataView><Buffer> 源被复制到 'Blob' 中,因此可以在创建 'Blob' 后安全地进行修改。

<ArrayBuffer>, <TypedArray>, <DataView>, and <Buffer> sources are copied into the 'Blob' and can therefore be safely modified after the 'Blob' is created.

字符串源被编码为 UTF-8 字节序列并复制到 Blob 中。每个字符串部分中不匹配的代理对将被替换为 Unicode U+FFFD 替换字符。

String sources are encoded as UTF-8 byte sequences and copied into the Blob. Unmatched surrogate pairs within each string part will be replaced by Unicode U+FFFD replacement characters.

blob.arrayBuffer()#

返回使用包含 Blob 数据副本的 <ArrayBuffer> 履行的 promise。

Returns a promise that fulfills with an <ArrayBuffer> containing a copy of the Blob data.

blob.size#

Blob 的总大小(以字节为单位)。

The total size of the Blob in bytes.

blob.slice([start[, end[, type]]])#

创建并返回包含此 Blob 对象数据子集的新 Blob。原来的 Blob 没有改动。

Creates and returns a new Blob containing a subset of this Blob objects data. The original Blob is not altered.

blob.stream()#

返回允许读取 Blob 内容的新 ReadableStream

Returns a new ReadableStream that allows the content of the Blob to be read.

blob.text()#

返回使用解码为 UTF-8 字符串的 Blob 的内容履行的 promise。

Returns a promise that fulfills with the contents of the Blob decoded as a UTF-8 string.

blob.type#

Blob 的内容类型。

The content-type of the Blob.

Blob 对象和 MessageChannel#

Blob objects and MessageChannel

一旦创建了 <Blob> 对象,就可以通过 MessagePort 将其发送到多个目标,而无需传输或立即复制数据。只有在调用 arrayBuffer()text() 方法时,才会复制 Blob 包含的数据。

Once a <Blob> object is created, it can be sent via MessagePort to multiple destinations without transferring or immediately copying the data. The data contained by the Blob is copied only when the arrayBuffer() or text() methods are called.

import { Blob } from 'node:buffer';
import { setTimeout as delay } from 'node:timers/promises';

const blob = new Blob(['hello there']);

const mc1 = new MessageChannel();
const mc2 = new MessageChannel();

mc1.port1.onmessage = async ({ data }) => {
  console.log(await data.arrayBuffer());
  mc1.port1.close();
};

mc2.port1.onmessage = async ({ data }) => {
  await delay(1000);
  console.log(await data.arrayBuffer());
  mc2.port1.close();
};

mc1.port2.postMessage(blob);
mc2.port2.postMessage(blob);

// The Blob is still usable after posting.
blob.text().then(console.log);const { Blob } = require('node:buffer');
const { setTimeout: delay } = require('node:timers/promises');

const blob = new Blob(['hello there']);

const mc1 = new MessageChannel();
const mc2 = new MessageChannel();

mc1.port1.onmessage = async ({ data }) => {
  console.log(await data.arrayBuffer());
  mc1.port1.close();
};

mc2.port1.onmessage = async ({ data }) => {
  await delay(1000);
  console.log(await data.arrayBuffer());
  mc2.port1.close();
};

mc1.port2.postMessage(blob);
mc2.port2.postMessage(blob);

// The Blob is still usable after posting.
blob.text().then(console.log);

类:Buffer#

Class: Buffer

Buffer 类是一个全局类型,用于直接处理二进制数据。它可以用多种方式构建。

The Buffer class is a global type for dealing with binary data directly. It can be constructed in a variety of ways.

静态方法:Buffer.alloc(size[, fill[, encoding]])#

Static method: Buffer.alloc(size[, fill[, encoding]])

分配 size 个字节的新 Buffer。如果 fillundefined,则 Buffer 将被填零。

Allocates a new Buffer of size bytes. If fill is undefined, the Buffer will be zero-filled.

import { Buffer } from 'node:buffer';

const buf = Buffer.alloc(5);

console.log(buf);
// Prints: <Buffer 00 00 00 00 00>const { Buffer } = require('node:buffer');

const buf = Buffer.alloc(5);

console.log(buf);
// Prints: <Buffer 00 00 00 00 00>

如果 size 大于 buffer.constants.MAX_LENGTH 或小于 0,则抛出 ERR_OUT_OF_RANGE

If size is larger than buffer.constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown.

如果指定了 fill,则分配的 Buffer 将通过调用 buf.fill(fill) 进行初始化。

If fill is specified, the allocated Buffer will be initialized by calling buf.fill(fill).

import { Buffer } from 'node:buffer';

const buf = Buffer.alloc(5, 'a');

console.log(buf);
// Prints: <Buffer 61 61 61 61 61>const { Buffer } = require('node:buffer');

const buf = Buffer.alloc(5, 'a');

console.log(buf);
// Prints: <Buffer 61 61 61 61 61>

如果同时指定了 fillencoding,则分配的 Buffer 将通过调用 buf.fill(fill, encoding) 进行初始化。

If both fill and encoding are specified, the allocated Buffer will be initialized by calling buf.fill(fill, encoding).

import { Buffer } from 'node:buffer';

const buf = Buffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');

console.log(buf);
// Prints: <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>const { Buffer } = require('node:buffer');

const buf = Buffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');

console.log(buf);
// Prints: <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>

调用 Buffer.alloc() 可能比替代 Buffer.allocUnsafe() 慢得多,但确保新创建的 Buffer 实例内容永远不会包含以前分配的敏感数据,包括可能没有为 Buffer 分配的数据。

Calling Buffer.alloc() can be measurably slower than the alternative Buffer.allocUnsafe() but ensures that the newly created Buffer instance contents will never contain sensitive data from previous allocations, including data that might not have been allocated for Buffers.

如果 size 不是数值,则会抛出 TypeError

A TypeError will be thrown if size is not a number.

静态方法:Buffer.allocUnsafe(size)#

Static method: Buffer.allocUnsafe(size)

  • size <integer> 新的 Buffer 所需的长度。

    size <integer> The desired length of the new Buffer.

分配 size 个字节的新 Buffer。如果 size 大于 buffer.constants.MAX_LENGTH 或小于 0,则抛出 ERR_OUT_OF_RANGE

Allocates a new Buffer of size bytes. If size is larger than buffer.constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown.

以这种方式创建的 Buffer 实例的底层内存没有被初始化。新创建的 Buffer 的内容未知,可能包含敏感数据。使用 Buffer.alloc() 来用零初始化 Buffer 实例。

The underlying memory for Buffer instances created in this way is not initialized. The contents of the newly created Buffer are unknown and may contain sensitive data. Use Buffer.alloc() instead to initialize Buffer instances with zeroes.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(10);

console.log(buf);
// Prints (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32>

buf.fill(0);

console.log(buf);
// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(10);

console.log(buf);
// Prints (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32>

buf.fill(0);

console.log(buf);
// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>

如果 size 不是数值,则会抛出 TypeError

A TypeError will be thrown if size is not a number.

Buffer 模块预分配一个大小为 Buffer.poolSize 的内部 Buffer 实例,仅当 size 小于 Buffer.poolSize >>> 1Buffer.poolSize 的下限除以 2)时,该实例用作快速分配使用 Buffer.allocUnsafe()Buffer.from(array)Buffer.concat() 创建的新 Buffer 实例的池。 。

The Buffer module pre-allocates an internal Buffer instance of size Buffer.poolSize that is used as a pool for the fast allocation of new Buffer instances created using Buffer.allocUnsafe(), Buffer.from(array), and Buffer.concat() only when size is less than Buffer.poolSize >>> 1 (floor of Buffer.poolSize divided by two).

使用此预先分配的内部内存池是调用 Buffer.alloc(size, fill) 与调用 Buffer.alloc(size, fill) 之间的关键区别。具体来说,Buffer.alloc(size, fill) 永远不会使用内部 Buffer 池,而如果 size 小于或等于 Buffer.poolSize 的一半,Buffer.allocUnsafe(size).fill(fill) 将使用内部 Buffer 池。当应用需要 Buffer.allocUnsafe() 提供的额外性能时,差异很细微,但可能很重要。

Use of this pre-allocated internal memory pool is a key difference between calling Buffer.alloc(size, fill) vs. Buffer.allocUnsafe(size).fill(fill). Specifically, Buffer.alloc(size, fill) will never use the internal Buffer pool, while Buffer.allocUnsafe(size).fill(fill) will use the internal Buffer pool if size is less than or equal to half Buffer.poolSize. The difference is subtle but can be important when an application requires the additional performance that Buffer.allocUnsafe() provides.

静态方法:Buffer.allocUnsafeSlow(size)#

Static method: Buffer.allocUnsafeSlow(size)

  • size <integer> 新的 Buffer 所需的长度。

    size <integer> The desired length of the new Buffer.

分配 size 个字节的新 Buffer。如果 size 大于 buffer.constants.MAX_LENGTH 或小于 0,则抛出 ERR_OUT_OF_RANGE。如果 size 为 0,则创建零长度 Buffer

Allocates a new Buffer of size bytes. If size is larger than buffer.constants.MAX_LENGTH or smaller than 0, ERR_OUT_OF_RANGE is thrown. A zero-length Buffer is created if size is 0.

以这种方式创建的 Buffer 实例的底层内存没有被初始化。新创建的 Buffer 的内容未知,可能包含敏感数据。使用 buf.fill(0) 用零初始化此类 Buffer 实例。

The underlying memory for Buffer instances created in this way is not initialized. The contents of the newly created Buffer are unknown and may contain sensitive data. Use buf.fill(0) to initialize such Buffer instances with zeroes.

当使用 Buffer.allocUnsafe() 分配新的 Buffer 实例时,4 KiB 以下的分配是从单个预分配的 Buffer 中分割出来的。这允许应用避免创建许多单独分配的 Buffer 实例的垃圾收集开销。这种方法无需跟踪和清理尽可能多的单个 ArrayBuffer 对象,从而提高了性能和内存使用率。

When using Buffer.allocUnsafe() to allocate new Buffer instances, allocations under 4 KiB are sliced from a single pre-allocated Buffer. This allows applications to avoid the garbage collection overhead of creating many individually allocated Buffer instances. This approach improves both performance and memory usage by eliminating the need to track and clean up as many individual ArrayBuffer objects.

但是,在开发者可能需要在不确定的时间内从池中保留一小块内存的情况下,使用 Buffer.allocUnsafeSlow() 创建未池化的 Buffer 实例然后复制出相关位可能是合适的。

However, in the case where a developer may need to retain a small chunk of memory from a pool for an indeterminate amount of time, it may be appropriate to create an un-pooled Buffer instance using Buffer.allocUnsafeSlow() and then copying out the relevant bits.

import { Buffer } from 'node:buffer';

// Need to keep around a few small chunks of memory.
const store = [];

socket.on('readable', () => {
  let data;
  while (null !== (data = readable.read())) {
    // Allocate for retained data.
    const sb = Buffer.allocUnsafeSlow(10);

    // Copy the data into the new allocation.
    data.copy(sb, 0, 0, 10);

    store.push(sb);
  }
});const { Buffer } = require('node:buffer');

// Need to keep around a few small chunks of memory.
const store = [];

socket.on('readable', () => {
  let data;
  while (null !== (data = readable.read())) {
    // Allocate for retained data.
    const sb = Buffer.allocUnsafeSlow(10);

    // Copy the data into the new allocation.
    data.copy(sb, 0, 0, 10);

    store.push(sb);
  }
});

如果 size 不是数值,则会抛出 TypeError

A TypeError will be thrown if size is not a number.

静态方法:Buffer.byteLength(string[, encoding])#

Static method: Buffer.byteLength(string[, encoding])

使用 encoding 编码时返回字符串的字节长度。这与 String.prototype.length 不同,String.prototype.length 不考虑用于将字符串转换为字节的编码。

Returns the byte length of a string when encoded using encoding. This is not the same as String.prototype.length, which does not account for the encoding that is used to convert the string into bytes.

对于 'base64''base64url''hex',此函数假定输入有效。对于包含非 base64/hex 编码数据(例如空格)的字符串,返回值可能大于从字符串创建的 Buffer 的长度。

For 'base64', 'base64url', and 'hex', this function assumes valid input. For strings that contain non-base64/hex-encoded data (e.g. whitespace), the return value might be greater than the length of a Buffer created from the string.

import { Buffer } from 'node:buffer';

const str = '\u00bd + \u00bc = \u00be';

console.log(`${str}: ${str.length} characters, ` +
            `${Buffer.byteLength(str, 'utf8')} bytes`);
// Prints: ½ + ¼ = ¾: 9 characters, 12 bytesconst { Buffer } = require('node:buffer');

const str = '\u00bd + \u00bc = \u00be';

console.log(`${str}: ${str.length} characters, ` +
            `${Buffer.byteLength(str, 'utf8')} bytes`);
// Prints: ½ + ¼ = ¾: 9 characters, 12 bytes

stringBuffer/DataView/TypedArray/ArrayBuffer/SharedArrayBuffer 时,返回 .byteLength 报告的字节长度。

When string is a Buffer/DataView/TypedArray/ArrayBuffer/ SharedArrayBuffer, the byte length as reported by .byteLength is returned.

静态方法:Buffer.compare(buf1, buf2)#

Static method: Buffer.compare(buf1, buf2)

比较 buf1buf2,通常用于对 Buffer 实例的数组进行排序。这相当于调用 buf1.compare(buf2)

Compares buf1 to buf2, typically for the purpose of sorting arrays of Buffer instances. This is equivalent to calling buf1.compare(buf2).

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from('1234');
const buf2 = Buffer.from('0123');
const arr = [buf1, buf2];

console.log(arr.sort(Buffer.compare));
// Prints: [ <Buffer 30 31 32 33>, <Buffer 31 32 33 34> ]
// (This result is equal to: [buf2, buf1].)const { Buffer } = require('node:buffer');

const buf1 = Buffer.from('1234');
const buf2 = Buffer.from('0123');
const arr = [buf1, buf2];

console.log(arr.sort(Buffer.compare));
// Prints: [ <Buffer 30 31 32 33>, <Buffer 31 32 33 34> ]
// (This result is equal to: [buf2, buf1].)

静态方法:Buffer.concat(list[, totalLength])#

Static method: Buffer.concat(list[, totalLength])

返回新的 Buffer,它是将 list 中的所有 Buffer 实例连接在一起的结果。

Returns a new Buffer which is the result of concatenating all the Buffer instances in the list together.

如果列表没有条目,或者 totalLength 为 0,则返回新的零长度 Buffer

If the list has no items, or if the totalLength is 0, then a new zero-length Buffer is returned.

如果未提供 totalLength,则从 list 中的 Buffer 实例通过相加其长度来计算。

If totalLength is not provided, it is calculated from the Buffer instances in list by adding their lengths.

如果提供了 totalLength,则将其强制为无符号整数。如果 list 中的 Buffer 的组合长度超过 totalLength,则结果将被截断为 totalLength

If totalLength is provided, it is coerced to an unsigned integer. If the combined length of the Buffers in list exceeds totalLength, the result is truncated to totalLength.

import { Buffer } from 'node:buffer';

// Create a single `Buffer` from a list of three `Buffer` instances.

const buf1 = Buffer.alloc(10);
const buf2 = Buffer.alloc(14);
const buf3 = Buffer.alloc(18);
const totalLength = buf1.length + buf2.length + buf3.length;

console.log(totalLength);
// Prints: 42

const bufA = Buffer.concat([buf1, buf2, buf3], totalLength);

console.log(bufA);
// Prints: <Buffer 00 00 00 00 ...>
console.log(bufA.length);
// Prints: 42const { Buffer } = require('node:buffer');

// Create a single `Buffer` from a list of three `Buffer` instances.

const buf1 = Buffer.alloc(10);
const buf2 = Buffer.alloc(14);
const buf3 = Buffer.alloc(18);
const totalLength = buf1.length + buf2.length + buf3.length;

console.log(totalLength);
// Prints: 42

const bufA = Buffer.concat([buf1, buf2, buf3], totalLength);

console.log(bufA);
// Prints: <Buffer 00 00 00 00 ...>
console.log(bufA.length);
// Prints: 42

Buffer.concat() 也像 Buffer.allocUnsafe() 一样使用内部 Buffer 池。

Buffer.concat() may also use the internal Buffer pool like Buffer.allocUnsafe() does.

静态方法:Buffer.copyBytesFrom(view[, offset[, length]])#

Static method: Buffer.copyBytesFrom(view[, offset[, length]])

view 的底层内存复制到新的 Buffer 中。

Copies the underlying memory of view into a new Buffer.

const u16 = new Uint16Array([0, 0xffff]);
const buf = Buffer.copyBytesFrom(u16, 1, 1);
u16[1] = 0;
console.log(buf.length); // 2
console.log(buf[0]); // 255
console.log(buf[1]); // 255 

静态方法:Buffer.from(array)#

Static method: Buffer.from(array)

使用 0255 范围内的 array 字节分配新的 Buffer。该范围之外的数组条目将被截断以符合它。

Allocates a new Buffer using an array of bytes in the range 0255. Array entries outside that range will be truncated to fit into it.

import { Buffer } from 'node:buffer';

// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'.
const buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);const { Buffer } = require('node:buffer');

// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'.
const buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);

如果 array 是类似 Array 的对象(即具有 number 类型的 length 属性的对象),则将其视为数组,除非它是 BufferUint8Array。这意味着所有其他 TypedArray 变体都被视为 Array。要从支持 TypedArray 的字节创建 Buffer,请使用 Buffer.copyBytesFrom()

If array is an Array-like object (that is, one with a length property of type number), it is treated as if it is an array, unless it is a Buffer or a Uint8Array. This means all other TypedArray variants get treated as an Array. To create a Buffer from the bytes backing a TypedArray, use Buffer.copyBytesFrom().

如果 array 不是 Array 或其他适用于 Buffer.from() 变体的类型,则将抛出 TypeError

A TypeError will be thrown if array is not an Array or another type appropriate for Buffer.from() variants.

Buffer.from(array)Buffer.from(string) 也像 Buffer.allocUnsafe() 一样使用内部 Buffer 池。

Buffer.from(array) and Buffer.from(string) may also use the internal Buffer pool like Buffer.allocUnsafe() does.

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

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

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>

可选的 byteOffsetlength 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

如果 arrayBuffer 不是 ArrayBufferSharedArrayBuffer 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 TypedArraybuffer 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>

静态方法:Buffer.from(buffer)#

Static method: Buffer.from(buffer)

将传入的 buffer 数据复制到新的 Buffer 实例上。

Copies the passed buffer data onto a new Buffer instance.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from('buffer');
const buf2 = Buffer.from(buf1);

buf1[0] = 0x61;

console.log(buf1.toString());
// Prints: auffer
console.log(buf2.toString());
// Prints: bufferconst { Buffer } = require('node:buffer');

const buf1 = Buffer.from('buffer');
const buf2 = Buffer.from(buf1);

buf1[0] = 0x61;

console.log(buf1.toString());
// Prints: auffer
console.log(buf2.toString());
// Prints: buffer

如果 buffer 不是 Buffer 或其他适用于 Buffer.from() 变体的类型,则将抛出 TypeError

A TypeError will be thrown if buffer is not a Buffer or another type appropriate for Buffer.from() variants.

静态方法:Buffer.from(object[, offsetOrEncoding[, length]])#

Static method: Buffer.from(object[, offsetOrEncoding[, length]])

对于 valueOf() 函数返回的值不严格等于 object 的对象,则返回 Buffer.from(object.valueOf(), offsetOrEncoding, length)

For objects whose valueOf() function returns a value not strictly equal to object, returns Buffer.from(object.valueOf(), offsetOrEncoding, length).

import { Buffer } from 'node:buffer';

const buf = Buffer.from(new String('this is a test'));
// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>const { Buffer } = require('node:buffer');

const buf = Buffer.from(new String('this is a test'));
// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>

对于支持 Symbol.toPrimitive 的对象,则返回 Buffer.from(object[Symbol.toPrimitive]('string'), offsetOrEncoding)

For objects that support Symbol.toPrimitive, returns Buffer.from(object[Symbol.toPrimitive]('string'), offsetOrEncoding).

import { Buffer } from 'node:buffer';

class Foo {
  [Symbol.toPrimitive]() {
    return 'this is a test';
  }
}

const buf = Buffer.from(new Foo(), 'utf8');
// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>const { Buffer } = require('node:buffer');

class Foo {
  [Symbol.toPrimitive]() {
    return 'this is a test';
  }
}

const buf = Buffer.from(new Foo(), 'utf8');
// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>

如果 object 没有提到的方法或不是适合 Buffer.from() 变体的另一种类型,则将抛出 TypeError

A TypeError will be thrown if object does not have the mentioned methods or is not of another type appropriate for Buffer.from() variants.

静态方法:Buffer.from(string[, encoding])#

Static method: Buffer.from(string[, encoding])

  • string <string> 要编码的字符串。

    string <string> A string to encode.

  • encoding <string> string 的编码。默认值:'utf8'

    encoding <string> The encoding of string. Default: 'utf8'.

创建包含 string 的新 Bufferencoding 参数标识将 string 转换为字节时要使用的字符编码。

Creates a new Buffer containing string. The encoding parameter identifies the character encoding to be used when converting string into bytes.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from('this is a tést');
const buf2 = Buffer.from('7468697320697320612074c3a97374', 'hex');

console.log(buf1.toString());
// Prints: this is a tést
console.log(buf2.toString());
// Prints: this is a tést
console.log(buf1.toString('latin1'));
// Prints: this is a téstconst { Buffer } = require('node:buffer');

const buf1 = Buffer.from('this is a tést');
const buf2 = Buffer.from('7468697320697320612074c3a97374', 'hex');

console.log(buf1.toString());
// Prints: this is a tést
console.log(buf2.toString());
// Prints: this is a tést
console.log(buf1.toString('latin1'));
// Prints: this is a tést

如果 string 不是字符串或其他适用于 Buffer.from() 变体的类型,则将抛出 TypeError

A TypeError will be thrown if string is not a string or another type appropriate for Buffer.from() variants.

静态方法:Buffer.isBuffer(obj)#

Static method: Buffer.isBuffer(obj)

如果 objBuffer,则返回 true,否则返回 false

Returns true if obj is a Buffer, false otherwise.

import { Buffer } from 'node:buffer';

Buffer.isBuffer(Buffer.alloc(10)); // true
Buffer.isBuffer(Buffer.from('foo')); // true
Buffer.isBuffer('a string'); // false
Buffer.isBuffer([]); // false
Buffer.isBuffer(new Uint8Array(1024)); // falseconst { Buffer } = require('node:buffer');

Buffer.isBuffer(Buffer.alloc(10)); // true
Buffer.isBuffer(Buffer.from('foo')); // true
Buffer.isBuffer('a string'); // false
Buffer.isBuffer([]); // false
Buffer.isBuffer(new Uint8Array(1024)); // false

静态方法:Buffer.isEncoding(encoding)#

Static method: Buffer.isEncoding(encoding)

如果 encoding 是支持的字符编码的名称,则返回 true,否则返回 false

Returns true if encoding is the name of a supported character encoding, or false otherwise.

import { Buffer } from 'node:buffer';

console.log(Buffer.isEncoding('utf8'));
// Prints: true

console.log(Buffer.isEncoding('hex'));
// Prints: true

console.log(Buffer.isEncoding('utf/8'));
// Prints: false

console.log(Buffer.isEncoding(''));
// Prints: falseconst { Buffer } = require('node:buffer');

console.log(Buffer.isEncoding('utf8'));
// Prints: true

console.log(Buffer.isEncoding('hex'));
// Prints: true

console.log(Buffer.isEncoding('utf/8'));
// Prints: false

console.log(Buffer.isEncoding(''));
// Prints: false

类属性:Buffer.poolSize#

Class property: Buffer.poolSize

这是用于池的预分配内部 Buffer 实例的大小(以字节为单位)。该值可以修改。

This is the size (in bytes) of pre-allocated internal Buffer instances used for pooling. This value may be modified.

buf[index]#

索引运算符 [index] 可用于获取和设置 buf 中位置 index 处的八位字节。这些值是指单个字节,因此合法值范围介于 0x000xFF(十六进制)或 0255(十进制)之间。

The index operator [index] can be used to get and set the octet at position index in buf. The values refer to individual bytes, so the legal value range is between 0x00 and 0xFF (hex) or 0 and 255 (decimal).

该运算符继承自 Uint8Array,因此其越界访问行为与 Uint8Array 相同。换句话说,当 index 为负或大于等于 buf.length 时,buf[index] 返回 undefined,如果 index 为负或 >= buf.lengthbuf[index] = value 不修改缓冲区。

This operator is inherited from Uint8Array, so its behavior on out-of-bounds access is the same as Uint8Array. In other words, buf[index] returns undefined when index is negative or greater or equal to buf.length, and buf[index] = value does not modify the buffer if index is negative or >= buf.length.

import { Buffer } from 'node:buffer';

// Copy an ASCII string into a `Buffer` one byte at a time.
// (This only works for ASCII-only strings. In general, one should use
// `Buffer.from()` to perform this conversion.)

const str = 'Node.js';
const buf = Buffer.allocUnsafe(str.length);

for (let i = 0; i < str.length; i++) {
  buf[i] = str.charCodeAt(i);
}

console.log(buf.toString('utf8'));
// Prints: Node.jsconst { Buffer } = require('node:buffer');

// Copy an ASCII string into a `Buffer` one byte at a time.
// (This only works for ASCII-only strings. In general, one should use
// `Buffer.from()` to perform this conversion.)

const str = 'Node.js';
const buf = Buffer.allocUnsafe(str.length);

for (let i = 0; i < str.length; i++) {
  buf[i] = str.charCodeAt(i);
}

console.log(buf.toString('utf8'));
// Prints: Node.js

buf.buffer#

  • <ArrayBuffer> 创建此 Buffer 对象所基于的基础 ArrayBuffer 对象。

    <ArrayBuffer> The underlying ArrayBuffer object based on which this Buffer object is created.

不保证此 ArrayBuffer 与原始 Buffer 完全对应。有关详细信息,请参阅 buf.byteOffset 上的说明。

This ArrayBuffer is not guaranteed to correspond exactly to the original Buffer. See the notes on buf.byteOffset for details.

import { Buffer } from 'node:buffer';

const arrayBuffer = new ArrayBuffer(16);
const buffer = Buffer.from(arrayBuffer);

console.log(buffer.buffer === arrayBuffer);
// Prints: trueconst { Buffer } = require('node:buffer');

const arrayBuffer = new ArrayBuffer(16);
const buffer = Buffer.from(arrayBuffer);

console.log(buffer.buffer === arrayBuffer);
// Prints: true

buf.byteOffset#

  • <integer> Buffer 底层 ArrayBuffer 对象的 byteOffset

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

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

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.

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。

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.

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

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);

buf.compare(target[, targetStart[, targetEnd[, sourceStart[, sourceEnd]]]])#

  • target <Buffer> | <Uint8Array> 用于比较 bufBufferUint8Array

    target <Buffer> | <Uint8Array> A Buffer or Uint8Array with which to compare buf.

  • targetStart <integer> target 内开始比较的偏移量。默认值:0

    targetStart <integer> The offset within target at which to begin comparison. Default: 0.

  • targetEnd <integer> target 中结束比较(不包括)的偏移量。默认值:target.length

    targetEnd <integer> The offset within target at which to end comparison (not inclusive). Default: target.length.

  • sourceStart <integer> buf 内开始比较的偏移量。默认值:0

    sourceStart <integer> The offset within buf at which to begin comparison. Default: 0.

  • sourceEnd <integer> buf 中结束比较(不包括)的偏移量。默认值:buf.length

    sourceEnd <integer> The offset within buf at which to end comparison (not inclusive). Default: buf.length.

  • 返回:<integer>

    Returns: <integer>

buftarget 进行比较并返回数字,该数字指示 buf 在排序顺序中是在 target 之前、之后还是与 target 相同。比较基于每个 Buffer 中的实际字节序列。

Compares buf with target and returns a number indicating whether buf comes before, after, or is the same as target in sort order. Comparison is based on the actual sequence of bytes in each Buffer.

  • 如果 targetbuf 相同,则返回 0

    0 is returned if target is the same as buf

  • 如果排序时 target 应该在 buf 之前,则返回 1

    1 is returned if target should come before buf when sorted.

  • 如果排序时 target 应该在 buf 之后,则返回 -1

    -1 is returned if target should come after buf when sorted.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('BCD');
const buf3 = Buffer.from('ABCD');

console.log(buf1.compare(buf1));
// Prints: 0
console.log(buf1.compare(buf2));
// Prints: -1
console.log(buf1.compare(buf3));
// Prints: -1
console.log(buf2.compare(buf1));
// Prints: 1
console.log(buf2.compare(buf3));
// Prints: 1
console.log([buf1, buf2, buf3].sort(Buffer.compare));
// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]
// (This result is equal to: [buf1, buf3, buf2].)const { Buffer } = require('node:buffer');

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('BCD');
const buf3 = Buffer.from('ABCD');

console.log(buf1.compare(buf1));
// Prints: 0
console.log(buf1.compare(buf2));
// Prints: -1
console.log(buf1.compare(buf3));
// Prints: -1
console.log(buf2.compare(buf1));
// Prints: 1
console.log(buf2.compare(buf3));
// Prints: 1
console.log([buf1, buf2, buf3].sort(Buffer.compare));
// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]
// (This result is equal to: [buf1, buf3, buf2].)

可选的 targetStarttargetEndsourceStartsourceEnd 参数可用于分别将比较限制在 targetbuf 内的特定范围内。

The optional targetStart, targetEnd, sourceStart, and sourceEnd arguments can be used to limit the comparison to specific ranges within target and buf respectively.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);

console.log(buf1.compare(buf2, 5, 9, 0, 4));
// Prints: 0
console.log(buf1.compare(buf2, 0, 6, 4));
// Prints: -1
console.log(buf1.compare(buf2, 5, 6, 5));
// Prints: 1const { Buffer } = require('node:buffer');

const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);

console.log(buf1.compare(buf2, 5, 9, 0, 4));
// Prints: 0
console.log(buf1.compare(buf2, 0, 6, 4));
// Prints: -1
console.log(buf1.compare(buf2, 5, 6, 5));
// Prints: 1

如果 targetStart < 0sourceStart < 0targetEnd > target.byteLengthsourceEnd > source.byteLength,则抛出 ERR_OUT_OF_RANGE

ERR_OUT_OF_RANGE is thrown if targetStart < 0, sourceStart < 0, targetEnd > target.byteLength, or sourceEnd > source.byteLength.

buf.copy(target[, targetStart[, sourceStart[, sourceEnd]]])#

  • target <Buffer> | <Uint8Array> 要复制到的 BufferUint8Array

    target <Buffer> | <Uint8Array> A Buffer or Uint8Array to copy into.

  • targetStart <integer> target 内开始写入的偏移量。默认值:0

    targetStart <integer> The offset within target at which to begin writing. Default: 0.

  • sourceStart <integer> buf 内开始复制的偏移量。默认值:0

    sourceStart <integer> The offset within buf from which to begin copying. Default: 0.

  • sourceEnd <integer> buf 内停止复制的偏移量(不包括)。默认值:buf.length

    sourceEnd <integer> The offset within buf at which to stop copying (not inclusive). Default: buf.length.

  • 返回:<integer> 复制的字节数。

    Returns: <integer> The number of bytes copied.

将数据从 buf 的区域复制到 target 的区域,即使 target 内存区域与 buf 重叠。

Copies data from a region of buf to a region in target, even if the target memory region overlaps with buf.

TypedArray.prototype.set() 执行相同的操作,并且可用于所有 TypedArrays,包括 Node.js Buffer,尽管它采用不同的函数参数。

TypedArray.prototype.set() performs the same operation, and is available for all TypedArrays, including Node.js Buffers, although it takes different function arguments.

import { Buffer } from 'node:buffer';

// Create two `Buffer` instances.
const buf1 = Buffer.allocUnsafe(26);
const buf2 = Buffer.allocUnsafe(26).fill('!');

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.
buf1.copy(buf2, 8, 16, 20);
// This is equivalent to:
// buf2.set(buf1.subarray(16, 20), 8);

console.log(buf2.toString('ascii', 0, 25));
// Prints: !!!!!!!!qrst!!!!!!!!!!!!!const { Buffer } = require('node:buffer');

// Create two `Buffer` instances.
const buf1 = Buffer.allocUnsafe(26);
const buf2 = Buffer.allocUnsafe(26).fill('!');

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.
buf1.copy(buf2, 8, 16, 20);
// This is equivalent to:
// buf2.set(buf1.subarray(16, 20), 8);

console.log(buf2.toString('ascii', 0, 25));
// Prints: !!!!!!!!qrst!!!!!!!!!!!!!
import { Buffer } from 'node:buffer';

// Create a `Buffer` and copy data from one region to an overlapping region
// within the same `Buffer`.

const buf = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf[i] = i + 97;
}

buf.copy(buf, 0, 4, 10);

console.log(buf.toString());
// Prints: efghijghijklmnopqrstuvwxyzconst { Buffer } = require('node:buffer');

// Create a `Buffer` and copy data from one region to an overlapping region
// within the same `Buffer`.

const buf = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf[i] = i + 97;
}

buf.copy(buf, 0, 4, 10);

console.log(buf.toString());
// Prints: efghijghijklmnopqrstuvwxyz

buf.entries()#

根据 buf 的内容创建并返回 迭代器[index, byte] 对。

Creates and returns an iterator of [index, byte] pairs from the contents of buf.

import { Buffer } from 'node:buffer';

// Log the entire contents of a `Buffer`.

const buf = Buffer.from('buffer');

for (const pair of buf.entries()) {
  console.log(pair);
}
// Prints:
//   [0, 98]
//   [1, 117]
//   [2, 102]
//   [3, 102]
//   [4, 101]
//   [5, 114]const { Buffer } = require('node:buffer');

// Log the entire contents of a `Buffer`.

const buf = Buffer.from('buffer');

for (const pair of buf.entries()) {
  console.log(pair);
}
// Prints:
//   [0, 98]
//   [1, 117]
//   [2, 102]
//   [3, 102]
//   [4, 101]
//   [5, 114]

buf.equals(otherBuffer)#

如果 bufotherBuffer 具有完全相同的字节,则返回 true,否则返回 false。相当于 buf.compare(otherBuffer) === 0

Returns true if both buf and otherBuffer have exactly the same bytes, false otherwise. Equivalent to buf.compare(otherBuffer) === 0.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('414243', 'hex');
const buf3 = Buffer.from('ABCD');

console.log(buf1.equals(buf2));
// Prints: true
console.log(buf1.equals(buf3));
// Prints: falseconst { Buffer } = require('node:buffer');

const buf1 = Buffer.from('ABC');
const buf2 = Buffer.from('414243', 'hex');
const buf3 = Buffer.from('ABCD');

console.log(buf1.equals(buf2));
// Prints: true
console.log(buf1.equals(buf3));
// Prints: false

buf.fill(value[, offset[, end]][, encoding])#

  • value <string> | <Buffer> | <Uint8Array> | <integer> 用于填充 buf 的值。空值(字符串、Uint8Array、缓冲区)被强制转换为 0

    value <string> | <Buffer> | <Uint8Array> | <integer> The value with which to fill buf. Empty value (string, Uint8Array, Buffer) is coerced to 0.

  • offset <integer> 在开始填充 buf 之前要跳过的字节数。默认值:0

    offset <integer> Number of bytes to skip before starting to fill buf. Default: 0.

  • end <integer> 停止填充 buf(不包括在内)的位置。默认值:buf.length

    end <integer> Where to stop filling buf (not inclusive). Default: buf.length.

  • encoding <string> 如果 value 是字符串,则为 value 的编码。默认值:'utf8'

    encoding <string> The encoding for value if value is a string. Default: 'utf8'.

  • 返回:<Buffer> buf 的引用。

    Returns: <Buffer> A reference to buf.

用指定的 value 填充 buf。如果没有给定 offsetend,则整个 buf 都会被填满:

Fills buf with the specified value. If the offset and end are not given, the entire buf will be filled:

import { Buffer } from 'node:buffer';

// Fill a `Buffer` with the ASCII character 'h'.

const b = Buffer.allocUnsafe(50).fill('h');

console.log(b.toString());
// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

// Fill a buffer with empty string
const c = Buffer.allocUnsafe(5).fill('');

console.log(c.fill(''));
// Prints: <Buffer 00 00 00 00 00>const { Buffer } = require('node:buffer');

// Fill a `Buffer` with the ASCII character 'h'.

const b = Buffer.allocUnsafe(50).fill('h');

console.log(b.toString());
// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh

// Fill a buffer with empty string
const c = Buffer.allocUnsafe(5).fill('');

console.log(c.fill(''));
// Prints: <Buffer 00 00 00 00 00>

如果 value 不是字符串、Buffer 或整数,则将其强制为 uint32 值。如果结果整数大于 255(十进制),则 buf 将填充 value & 255

value is coerced to a uint32 value if it is not a string, Buffer, or integer. If the resulting integer is greater than 255 (decimal), buf will be filled with value & 255.

如果 fill() 操作的最终写入落在多字节字符上,则仅写入适合 buf 的该字符的字节:

If the final write of a fill() operation falls on a multi-byte character, then only the bytes of that character that fit into buf are written:

import { Buffer } from 'node:buffer';

// Fill a `Buffer` with character that takes up two bytes in UTF-8.

console.log(Buffer.allocUnsafe(5).fill('\u0222'));
// Prints: <Buffer c8 a2 c8 a2 c8>const { Buffer } = require('node:buffer');

// Fill a `Buffer` with character that takes up two bytes in UTF-8.

console.log(Buffer.allocUnsafe(5).fill('\u0222'));
// Prints: <Buffer c8 a2 c8 a2 c8>

如果 value 包含无效字符,则将其截断;如果没有有效的填充数据,则抛出异常:

If value contains invalid characters, it is truncated; if no valid fill data remains, an exception is thrown:

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(5);

console.log(buf.fill('a'));
// Prints: <Buffer 61 61 61 61 61>
console.log(buf.fill('aazz', 'hex'));
// Prints: <Buffer aa aa aa aa aa>
console.log(buf.fill('zz', 'hex'));
// Throws an exception.const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(5);

console.log(buf.fill('a'));
// Prints: <Buffer 61 61 61 61 61>
console.log(buf.fill('aazz', 'hex'));
// Prints: <Buffer aa aa aa aa aa>
console.log(buf.fill('zz', 'hex'));
// Throws an exception.

buf.includes(value[, byteOffset][, encoding])#

  • value <string> | <Buffer> | <Uint8Array> | <integer> 要搜索的内容。

    value <string> | <Buffer> | <Uint8Array> | <integer> What to search for.

  • byteOffset <integer> 开始搜索 buf 的位置。如果为负数,则从 buf 的末尾开始计算偏移量。默认值:0

    byteOffset <integer> Where to begin searching in buf. If negative, then offset is calculated from the end of buf. Default: 0.

  • encoding <string> 如果 value 是字符串,则这就是它的编码。默认值:'utf8'

    encoding <string> If value is a string, this is its encoding. Default: 'utf8'.

  • 返回:<boolean> 如果在 buf 中找到 value,则为 true,否则为 false

    Returns: <boolean> true if value was found in buf, false otherwise.

相当于 buf.indexOf() !== -1

Equivalent to buf.indexOf() !== -1.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.includes('this'));
// Prints: true
console.log(buf.includes('is'));
// Prints: true
console.log(buf.includes(Buffer.from('a buffer')));
// Prints: true
console.log(buf.includes(97));
// Prints: true (97 is the decimal ASCII value for 'a')
console.log(buf.includes(Buffer.from('a buffer example')));
// Prints: false
console.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));
// Prints: true
console.log(buf.includes('this', 4));
// Prints: falseconst { Buffer } = require('node:buffer');

const buf = Buffer.from('this is a buffer');

console.log(buf.includes('this'));
// Prints: true
console.log(buf.includes('is'));
// Prints: true
console.log(buf.includes(Buffer.from('a buffer')));
// Prints: true
console.log(buf.includes(97));
// Prints: true (97 is the decimal ASCII value for 'a')
console.log(buf.includes(Buffer.from('a buffer example')));
// Prints: false
console.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));
// Prints: true
console.log(buf.includes('this', 4));
// Prints: false

buf.indexOf(value[, byteOffset][, encoding])#

  • value <string> | <Buffer> | <Uint8Array> | <integer> 要搜索的内容。

    value <string> | <Buffer> | <Uint8Array> | <integer> What to search for.

  • byteOffset <integer> 开始搜索 buf 的位置。如果为负数,则从 buf 的末尾开始计算偏移量。默认值:0

    byteOffset <integer> Where to begin searching in buf. If negative, then offset is calculated from the end of buf. Default: 0.

  • encoding <string> 如果 value 是字符串,则这是用于确定将在 buf 中搜索的字符串的二进制表示的编码。默认值:'utf8'

    encoding <string> If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf. Default: 'utf8'.

  • 返回:<integer> buf 中第一次出现 value 的索引,如果 buf 不包含 value,则为 -1

    Returns: <integer> The index of the first occurrence of value in buf, or -1 if buf does not contain value.

如果 value 是:

If value is:

  • 字符串,value 根据 encoding 中的字符编码进行解释。

    a string, value is interpreted according to the character encoding in encoding.

  • BufferUint8Array, value 将全部使用。要比较部分 Buffer,则使用 buf.subarray

    a Buffer or Uint8Array, value will be used in its entirety. To compare a partial Buffer, use buf.subarray.

  • 数字,value 将被解释为 0255 之间的无符号 8 位整数值。

    a number, value will be interpreted as an unsigned 8-bit integer value between 0 and 255.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('this is a buffer');

console.log(buf.indexOf('this'));
// Prints: 0
console.log(buf.indexOf('is'));
// Prints: 2
console.log(buf.indexOf(Buffer.from('a buffer')));
// Prints: 8
console.log(buf.indexOf(97));
// Prints: 8 (97 is the decimal ASCII value for 'a')
console.log(buf.indexOf(Buffer.from('a buffer example')));
// Prints: -1
console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
// Prints: 8

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.indexOf('\u03a3', 0, 'utf16le'));
// Prints: 4
console.log(utf16Buffer.indexOf('\u03a3', -4, 'utf16le'));
// Prints: 6const { Buffer } = require('node:buffer');

const buf = Buffer.from('this is a buffer');

console.log(buf.indexOf('this'));
// Prints: 0
console.log(buf.indexOf('is'));
// Prints: 2
console.log(buf.indexOf(Buffer.from('a buffer')));
// Prints: 8
console.log(buf.indexOf(97));
// Prints: 8 (97 is the decimal ASCII value for 'a')
console.log(buf.indexOf(Buffer.from('a buffer example')));
// Prints: -1
console.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));
// Prints: 8

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.indexOf('\u03a3', 0, 'utf16le'));
// Prints: 4
console.log(utf16Buffer.indexOf('\u03a3', -4, 'utf16le'));
// Prints: 6

如果 value 不是字符串、数字或 Buffer,则此方法将抛出 TypeError。如果 value 是数字,则它将被强制转换为有效的字节值(0 到 255 之间的整数)。

If value is not a string, number, or Buffer, this method will throw a TypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

如果 byteOffset 不是数字,则会被强制为数字。如果强制转换的结果是 NaN0,则将搜索整个缓冲区。此行为与 String.prototype.indexOf() 匹配。

If byteOffset is not a number, it will be coerced to a number. If the result of coercion is NaN or 0, then the entire buffer will be searched. This behavior matches String.prototype.indexOf().

import { Buffer } from 'node:buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.indexOf(99.9));
console.log(b.indexOf(256 + 99));

// Passing a byteOffset that coerces to NaN or 0.
// Prints: 1, searching the whole buffer.
console.log(b.indexOf('b', undefined));
console.log(b.indexOf('b', {}));
console.log(b.indexOf('b', null));
console.log(b.indexOf('b', []));const { Buffer } = require('node:buffer');

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.indexOf(99.9));
console.log(b.indexOf(256 + 99));

// Passing a byteOffset that coerces to NaN or 0.
// Prints: 1, searching the whole buffer.
console.log(b.indexOf('b', undefined));
console.log(b.indexOf('b', {}));
console.log(b.indexOf('b', null));
console.log(b.indexOf('b', []));

如果 value 为空字符串或空 BufferbyteOffset 小于 buf.length,则返回 byteOffset。如果 value 为空且 byteOffset 至少为 buf.length,则返回 buf.length

If value is an empty string or empty Buffer and byteOffset is less than buf.length, byteOffset will be returned. If value is empty and byteOffset is at least buf.length, buf.length will be returned.

buf.keys()#

创建并返回 迭代器buf 键(索引)。

Creates and returns an iterator of buf keys (indices).

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

for (const key of buf.keys()) {
  console.log(key);
}
// Prints:
//   0
//   1
//   2
//   3
//   4
//   5const { Buffer } = require('node:buffer');

const buf = Buffer.from('buffer');

for (const key of buf.keys()) {
  console.log(key);
}
// Prints:
//   0
//   1
//   2
//   3
//   4
//   5

buf.lastIndexOf(value[, byteOffset][, encoding])#

  • value <string> | <Buffer> | <Uint8Array> | <integer> 要搜索的内容。

    value <string> | <Buffer> | <Uint8Array> | <integer> What to search for.

  • byteOffset <integer> 开始搜索 buf 的位置。如果为负数,则从 buf 的末尾开始计算偏移量。默认值:buf.length - 1

    byteOffset <integer> Where to begin searching in buf. If negative, then offset is calculated from the end of buf. Default: buf.length - 1.

  • encoding <string> 如果 value 是字符串,则这是用于确定将在 buf 中搜索的字符串的二进制表示的编码。默认值:'utf8'

    encoding <string> If value is a string, this is the encoding used to determine the binary representation of the string that will be searched for in buf. Default: 'utf8'.

  • 返回:<integer> buf 中最后一次出现 value 的索引,如果 buf 不包含 value,则为 -1

    Returns: <integer> The index of the last occurrence of value in buf, or -1 if buf does not contain value.

buf.indexOf() 相同,除了找到最后一次出现的 value 而不是第一次出现。

Identical to buf.indexOf(), except the last occurrence of value is found rather than the first occurrence.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('this buffer is a buffer');

console.log(buf.lastIndexOf('this'));
// Prints: 0
console.log(buf.lastIndexOf('buffer'));
// Prints: 17
console.log(buf.lastIndexOf(Buffer.from('buffer')));
// Prints: 17
console.log(buf.lastIndexOf(97));
// Prints: 15 (97 is the decimal ASCII value for 'a')
console.log(buf.lastIndexOf(Buffer.from('yolo')));
// Prints: -1
console.log(buf.lastIndexOf('buffer', 5));
// Prints: 5
console.log(buf.lastIndexOf('buffer', 4));
// Prints: -1

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le'));
// Prints: 6
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le'));
// Prints: 4const { Buffer } = require('node:buffer');

const buf = Buffer.from('this buffer is a buffer');

console.log(buf.lastIndexOf('this'));
// Prints: 0
console.log(buf.lastIndexOf('buffer'));
// Prints: 17
console.log(buf.lastIndexOf(Buffer.from('buffer')));
// Prints: 17
console.log(buf.lastIndexOf(97));
// Prints: 15 (97 is the decimal ASCII value for 'a')
console.log(buf.lastIndexOf(Buffer.from('yolo')));
// Prints: -1
console.log(buf.lastIndexOf('buffer', 5));
// Prints: 5
console.log(buf.lastIndexOf('buffer', 4));
// Prints: -1

const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'utf16le');

console.log(utf16Buffer.lastIndexOf('\u03a3', undefined, 'utf16le'));
// Prints: 6
console.log(utf16Buffer.lastIndexOf('\u03a3', -5, 'utf16le'));
// Prints: 4

如果 value 不是字符串、数字或 Buffer,则此方法将抛出 TypeError。如果 value 是数字,则它将被强制转换为有效的字节值(0 到 255 之间的整数)。

If value is not a string, number, or Buffer, this method will throw a TypeError. If value is a number, it will be coerced to a valid byte value, an integer between 0 and 255.

如果 byteOffset 不是数字,则会被强制为数字。任何强制到 NaN 的参数,如 {}undefined,都将搜索整个缓冲区。此行为与 String.prototype.lastIndexOf() 匹配。

If byteOffset is not a number, it will be coerced to a number. Any arguments that coerce to NaN, like {} or undefined, will search the whole buffer. This behavior matches String.prototype.lastIndexOf().

import { Buffer } from 'node:buffer';

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.lastIndexOf(99.9));
console.log(b.lastIndexOf(256 + 99));

// Passing a byteOffset that coerces to NaN.
// Prints: 1, searching the whole buffer.
console.log(b.lastIndexOf('b', undefined));
console.log(b.lastIndexOf('b', {}));

// Passing a byteOffset that coerces to 0.
// Prints: -1, equivalent to passing 0.
console.log(b.lastIndexOf('b', null));
console.log(b.lastIndexOf('b', []));const { Buffer } = require('node:buffer');

const b = Buffer.from('abcdef');

// Passing a value that's a number, but not a valid byte.
// Prints: 2, equivalent to searching for 99 or 'c'.
console.log(b.lastIndexOf(99.9));
console.log(b.lastIndexOf(256 + 99));

// Passing a byteOffset that coerces to NaN.
// Prints: 1, searching the whole buffer.
console.log(b.lastIndexOf('b', undefined));
console.log(b.lastIndexOf('b', {}));

// Passing a byteOffset that coerces to 0.
// Prints: -1, equivalent to passing 0.
console.log(b.lastIndexOf('b', null));
console.log(b.lastIndexOf('b', []));

如果 value 为空字符串或空 Buffer,则返回 byteOffset

If value is an empty string or empty Buffer, byteOffset will be returned.

buf.length#

返回 buf 中的字节数。

Returns the number of bytes in buf.

import { Buffer } from 'node:buffer';

// Create a `Buffer` and write a shorter string to it using UTF-8.

const buf = Buffer.alloc(1234);

console.log(buf.length);
// Prints: 1234

buf.write('some string', 0, 'utf8');

console.log(buf.length);
// Prints: 1234const { Buffer } = require('node:buffer');

// Create a `Buffer` and write a shorter string to it using UTF-8.

const buf = Buffer.alloc(1234);

console.log(buf.length);
// Prints: 1234

buf.write('some string', 0, 'utf8');

console.log(buf.length);
// Prints: 1234

buf.parent#

稳定性: 0 - 已弃用:改用 buf.buffer

Stability: 0 - Deprecated: Use buf.buffer instead.

buf.parent 属性是 buf.buffer 的弃用别名。

The buf.parent property is a deprecated alias for buf.buffer.

buf.readBigInt64BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<bigint>

    Returns: <bigint>

从指定的 offset 处的 buf 读取有符号的大端序 64 位整数。

Reads a signed, big-endian 64-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

buf.readBigInt64LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<bigint>

    Returns: <bigint>

从指定的 offset 处的 buf 读取有符号的小端序 64 位整数。

Reads a signed, little-endian 64-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

buf.readBigUInt64BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<bigint>

    Returns: <bigint>

从指定的 offset 处的 buf 读取无符号的大端序 64 位整数。

Reads an unsigned, big-endian 64-bit integer from buf at the specified offset.

此函数也可在 readBigUint64BE 别名下使用。

This function is also available under the readBigUint64BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64BE(0));
// Prints: 4294967295nconst { Buffer } = require('node:buffer');

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64BE(0));
// Prints: 4294967295n

buf.readBigUInt64LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<bigint>

    Returns: <bigint>

从指定的 offset 处的 buf 读取无符号的小端序 64 位整数。

Reads an unsigned, little-endian 64-bit integer from buf at the specified offset.

此函数也可在 readBigUint64LE 别名下使用。

This function is also available under the readBigUint64LE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64LE(0));
// Prints: 18446744069414584320nconst { Buffer } = require('node:buffer');

const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);

console.log(buf.readBigUInt64LE(0));
// Prints: 18446744069414584320n

buf.readDoubleBE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<number>

    Returns: <number>

从指定 offset 处的 buf 读取 64 位大端序双精度值。

Reads a 64-bit, big-endian double from buf at the specified offset.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleBE(0));
// Prints: 8.20788039913184e-304const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleBE(0));
// Prints: 8.20788039913184e-304

buf.readDoubleLE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<number>

    Returns: <number>

从指定 offset 处的 buf 读取 64 位小端序双精度值。

Reads a 64-bit, little-endian double from buf at the specified offset.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleLE(0));
// Prints: 5.447603722011605e-270
console.log(buf.readDoubleLE(1));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);

console.log(buf.readDoubleLE(0));
// Prints: 5.447603722011605e-270
console.log(buf.readDoubleLE(1));
// Throws ERR_OUT_OF_RANGE.

buf.readFloatBE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<number>

    Returns: <number>

从指定 offset 处的 buf 读取 32 位大端序浮点数。

Reads a 32-bit, big-endian float from buf at the specified offset.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatBE(0));
// Prints: 2.387939260590663e-38const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatBE(0));
// Prints: 2.387939260590663e-38

buf.readFloatLE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<number>

    Returns: <number>

从指定 offset 处的 buf 读取 32 位小端序浮点数。

Reads a 32-bit, little-endian float from buf at the specified offset.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatLE(0));
// Prints: 1.539989614439558e-36
console.log(buf.readFloatLE(1));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, 2, 3, 4]);

console.log(buf.readFloatLE(0));
// Prints: 1.539989614439558e-36
console.log(buf.readFloatLE(1));
// Throws ERR_OUT_OF_RANGE.

buf.readInt8([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 1。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取有符号的 8 位整数。

Reads a signed 8-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([-1, 5]);

console.log(buf.readInt8(0));
// Prints: -1
console.log(buf.readInt8(1));
// Prints: 5
console.log(buf.readInt8(2));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([-1, 5]);

console.log(buf.readInt8(0));
// Prints: -1
console.log(buf.readInt8(1));
// Prints: 5
console.log(buf.readInt8(2));
// Throws ERR_OUT_OF_RANGE.

buf.readInt16BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取有符号的大端序 16 位整数。

Reads a signed, big-endian 16-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16BE(0));
// Prints: 5const { Buffer } = require('node:buffer');

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16BE(0));
// Prints: 5

buf.readInt16LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取有符号的小端序 16 位整数。

Reads a signed, little-endian 16-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16LE(0));
// Prints: 1280
console.log(buf.readInt16LE(1));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0, 5]);

console.log(buf.readInt16LE(0));
// Prints: 1280
console.log(buf.readInt16LE(1));
// Throws ERR_OUT_OF_RANGE.

buf.readInt32BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取有符号的大端序 32 位整数。

Reads a signed, big-endian 32-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32BE(0));
// Prints: 5const { Buffer } = require('node:buffer');

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32BE(0));
// Prints: 5

buf.readInt32LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取有符号的小端序 32 位整数。

Reads a signed, little-endian 32-bit integer from buf at the specified offset.

Buffer 读取的整数被解释为二进制补码有符号值。

Integers read from a Buffer are interpreted as two's complement signed values.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32LE(0));
// Prints: 83886080
console.log(buf.readInt32LE(1));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0, 0, 0, 5]);

console.log(buf.readInt32LE(0));
// Prints: 83886080
console.log(buf.readInt32LE(1));
// Throws ERR_OUT_OF_RANGE.

buf.readIntBE(offset, byteLength)#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要读取的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to read. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取 byteLength 个字节,并将结果解释为支持最高 48 位精度的大端序、二进制补码有符号值。

Reads byteLength number of bytes from buf at the specified offset and interprets the result as a big-endian, two's complement signed value supporting up to 48 bits of accuracy.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
console.log(buf.readIntBE(1, 0).toString(16));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.
console.log(buf.readIntBE(1, 0).toString(16));
// Throws ERR_OUT_OF_RANGE.

buf.readIntLE(offset, byteLength)#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要读取的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to read. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取 byteLength 个字节,并将结果解释为支持最高 48 位精度的小端序、二进制补码有符号值。

Reads byteLength number of bytes from buf at the specified offset and interprets the result as a little-endian, two's complement signed value supporting up to 48 bits of accuracy.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntLE(0, 6).toString(16));
// Prints: -546f87a9cbeeconst { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readIntLE(0, 6).toString(16));
// Prints: -546f87a9cbee

buf.readUInt8([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 1。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 1. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定 offset 处的 buf 读取无符号 8 位整数。

Reads an unsigned 8-bit integer from buf at the specified offset.

此函数也可在 readUint8 别名下使用。

This function is also available under the readUint8 alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([1, -2]);

console.log(buf.readUInt8(0));
// Prints: 1
console.log(buf.readUInt8(1));
// Prints: 254
console.log(buf.readUInt8(2));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([1, -2]);

console.log(buf.readUInt8(0));
// Prints: 1
console.log(buf.readUInt8(1));
// Prints: 254
console.log(buf.readUInt8(2));
// Throws ERR_OUT_OF_RANGE.

buf.readUInt16BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取无符号的大端序 16 位整数。

Reads an unsigned, big-endian 16-bit integer from buf at the specified offset.

此函数也可在 readUint16BE 别名下使用。

This function is also available under the readUint16BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16BE(0).toString(16));
// Prints: 1234
console.log(buf.readUInt16BE(1).toString(16));
// Prints: 3456const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16BE(0).toString(16));
// Prints: 1234
console.log(buf.readUInt16BE(1).toString(16));
// Prints: 3456

buf.readUInt16LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取无符号的小端序 16 位整数。

Reads an unsigned, little-endian 16-bit integer from buf at the specified offset.

此函数也可在 readUint16LE 别名下使用。

This function is also available under the readUint16LE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16LE(0).toString(16));
// Prints: 3412
console.log(buf.readUInt16LE(1).toString(16));
// Prints: 5634
console.log(buf.readUInt16LE(2).toString(16));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56]);

console.log(buf.readUInt16LE(0).toString(16));
// Prints: 3412
console.log(buf.readUInt16LE(1).toString(16));
// Prints: 5634
console.log(buf.readUInt16LE(2).toString(16));
// Throws ERR_OUT_OF_RANGE.

buf.readUInt32BE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取无符号的大端序 32 位整数。

Reads an unsigned, big-endian 32-bit integer from buf at the specified offset.

此函数也可在 readUint32BE 别名下使用。

This function is also available under the readUint32BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32BE(0).toString(16));
// Prints: 12345678const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32BE(0).toString(16));
// Prints: 12345678

buf.readUInt32LE([offset])#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取无符号的小端序 32 位整数。

Reads an unsigned, little-endian 32-bit integer from buf at the specified offset.

此函数也可在 readUint32LE 别名下使用。

This function is also available under the readUint32LE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32LE(0).toString(16));
// Prints: 78563412
console.log(buf.readUInt32LE(1).toString(16));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);

console.log(buf.readUInt32LE(0).toString(16));
// Prints: 78563412
console.log(buf.readUInt32LE(1).toString(16));
// Throws ERR_OUT_OF_RANGE.

buf.readUIntBE(offset, byteLength)#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要读取的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to read. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取 byteLength 个字节,并将结果解释为支持最高 48 位精度的无符号大端序整数。

Reads byteLength number of bytes from buf at the specified offset and interprets the result as an unsigned big-endian integer supporting up to 48 bits of accuracy.

此函数也可在 readUintBE 别名下使用。

This function is also available under the readUintBE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readUIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntBE(0, 6).toString(16));
// Prints: 1234567890ab
console.log(buf.readUIntBE(1, 6).toString(16));
// Throws ERR_OUT_OF_RANGE.

buf.readUIntLE(offset, byteLength)#

  • offset <integer> 开始读取之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to read. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要读取的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to read. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer>

    Returns: <integer>

从指定的 offset 处的 buf 读取 byteLength 个字节,并将结果解释为支持最高 48 位精度的无符号小端序整数。

Reads byteLength number of bytes from buf at the specified offset and interprets the result as an unsigned, little-endian integer supporting up to 48 bits of accuracy.

此函数也可在 readUintLE 别名下使用。

This function is also available under the readUintLE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntLE(0, 6).toString(16));
// Prints: ab9078563412const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);

console.log(buf.readUIntLE(0, 6).toString(16));
// Prints: ab9078563412

buf.subarray([start[, end]])#

返回新的 Buffer,其引用与原始缓冲区相同的内存,但由 startend 索引进行偏移和裁剪。

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

指定 end 大于 buf.length 将返回与 end 等于 buf.length 相同的结果。

Specifying end greater than buf.length will return the same result as that of end equal to buf.length.

该方法继承自 TypedArray.prototype.subarray()

This method is inherited from TypedArray.prototype.subarray().

修改新的 Buffer 切片会修改原来 Buffer 中的内存,因为两个对象分配的内存是重叠的。

Modifying the new Buffer slice will modify the memory in the original Buffer because the allocated memory of the two objects overlap.

import { Buffer } from 'node:buffer';

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bcconst { Buffer } = require('node:buffer');

// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte
// from the original `Buffer`.

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

const buf2 = buf1.subarray(0, 3);

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: abc

buf1[0] = 33;

console.log(buf2.toString('ascii', 0, buf2.length));
// Prints: !bc

指定负索引会导致相对于 buf 的末尾而不是开头生成切片。

Specifying negative indexes causes the slice to be generated relative to the end of buf rather than the beginning.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)const { Buffer } = require('node:buffer');

const buf = Buffer.from('buffer');

console.log(buf.subarray(-6, -1).toString());
// Prints: buffe
// (Equivalent to buf.subarray(0, 5).)

console.log(buf.subarray(-6, -2).toString());
// Prints: buff
// (Equivalent to buf.subarray(0, 4).)

console.log(buf.subarray(-5, -2).toString());
// Prints: uff
// (Equivalent to buf.subarray(1, 4).)

buf.slice([start[, end]])#

稳定性: 0 - 已弃用:改用 buf.subarray

Stability: 0 - Deprecated: Use buf.subarray instead.

返回新的 Buffer,其引用与原始缓冲区相同的内存,但由 startend 索引进行偏移和裁剪。

Returns a new Buffer that references the same memory as the original, but offset and cropped by the start and end indices.

此方法与 Uint8Array.prototype.slice()Buffer 的超类)不兼容。要复制切片,则使用 Uint8Array.prototype.slice()

This method is not compatible with the Uint8Array.prototype.slice(), which is a superclass of Buffer. To copy the slice, use Uint8Array.prototype.slice().

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

const copiedBuf = Uint8Array.prototype.slice.call(buf);
copiedBuf[0]++;
console.log(copiedBuf.toString());
// Prints: cuffer

console.log(buf.toString());
// Prints: buffer

// With buf.slice(), the original buffer is modified.
const notReallyCopiedBuf = buf.slice();
notReallyCopiedBuf[0]++;
console.log(notReallyCopiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Also prints: cuffer (!)const { Buffer } = require('node:buffer');

const buf = Buffer.from('buffer');

const copiedBuf = Uint8Array.prototype.slice.call(buf);
copiedBuf[0]++;
console.log(copiedBuf.toString());
// Prints: cuffer

console.log(buf.toString());
// Prints: buffer

// With buf.slice(), the original buffer is modified.
const notReallyCopiedBuf = buf.slice();
notReallyCopiedBuf[0]++;
console.log(notReallyCopiedBuf.toString());
// Prints: cuffer
console.log(buf.toString());
// Also prints: cuffer (!)

buf.swap16()#

buf 解释为无符号 16 位整数数组,并就地交换字节顺序。如果 buf.length 不是 2 的倍数,则抛出 ERR_INVALID_BUFFER_SIZE

Interprets buf as an array of unsigned 16-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 2.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap16();

console.log(buf1);
// Prints: <Buffer 02 01 04 03 06 05 08 07>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap16();
// Throws ERR_INVALID_BUFFER_SIZE.const { Buffer } = require('node:buffer');

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap16();

console.log(buf1);
// Prints: <Buffer 02 01 04 03 06 05 08 07>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap16();
// Throws ERR_INVALID_BUFFER_SIZE.

buf.swap16() 的一种方便用法是在 UTF-16 小端序和 UTF-16 大端序之间执行快速就地转换:

One convenient use of buf.swap16() is to perform a fast in-place conversion between UTF-16 little-endian and UTF-16 big-endian:

import { Buffer } from 'node:buffer';

const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');
buf.swap16(); // Convert to big-endian UTF-16 text.const { Buffer } = require('node:buffer');

const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');
buf.swap16(); // Convert to big-endian UTF-16 text.

buf.swap32()#

buf 解释为无符号 32 位整数数组,并就地交换字节顺序。如果 buf.length 不是 4 的倍数,则抛出 ERR_INVALID_BUFFER_SIZE

Interprets buf as an array of unsigned 32-bit integers and swaps the byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 4.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap32();

console.log(buf1);
// Prints: <Buffer 04 03 02 01 08 07 06 05>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap32();
// Throws ERR_INVALID_BUFFER_SIZE.const { Buffer } = require('node:buffer');

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap32();

console.log(buf1);
// Prints: <Buffer 04 03 02 01 08 07 06 05>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap32();
// Throws ERR_INVALID_BUFFER_SIZE.

buf.swap64()#

buf 解释为 64 位数字数组并就地交换字节顺序。如果 buf.length 不是 8 的倍数,则抛出 ERR_INVALID_BUFFER_SIZE

Interprets buf as an array of 64-bit numbers and swaps byte order in-place. Throws ERR_INVALID_BUFFER_SIZE if buf.length is not a multiple of 8.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap64();

console.log(buf1);
// Prints: <Buffer 08 07 06 05 04 03 02 01>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap64();
// Throws ERR_INVALID_BUFFER_SIZE.const { Buffer } = require('node:buffer');

const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);

console.log(buf1);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf1.swap64();

console.log(buf1);
// Prints: <Buffer 08 07 06 05 04 03 02 01>

const buf2 = Buffer.from([0x1, 0x2, 0x3]);

buf2.swap64();
// Throws ERR_INVALID_BUFFER_SIZE.

buf.toJSON()#

返回 buf 的 JSON 表示。JSON.stringify() 在字符串化 Buffer 实例时隐式调用此函数。

Returns a JSON representation of buf. JSON.stringify() implicitly calls this function when stringifying a Buffer instance.

Buffer.from() 接受从此方法返回的格式的对象。特别是,Buffer.from(buf.toJSON()) 的工作方式类似于 Buffer.from(buf)

Buffer.from() accepts objects in the format returned from this method. In particular, Buffer.from(buf.toJSON()) works like Buffer.from(buf).

import { Buffer } from 'node:buffer';

const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);

console.log(json);
// Prints: {"type":"Buffer","data":[1,2,3,4,5]}

const copy = JSON.parse(json, (key, value) => {
  return value && value.type === 'Buffer' ?
    Buffer.from(value) :
    value;
});

console.log(copy);
// Prints: <Buffer 01 02 03 04 05>const { Buffer } = require('node:buffer');

const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);
const json = JSON.stringify(buf);

console.log(json);
// Prints: {"type":"Buffer","data":[1,2,3,4,5]}

const copy = JSON.parse(json, (key, value) => {
  return value && value.type === 'Buffer' ?
    Buffer.from(value) :
    value;
});

console.log(copy);
// Prints: <Buffer 01 02 03 04 05>

buf.toString([encoding[, start[, end]]])#

  • encoding <string> 要使用的字符编码。默认值:'utf8'

    encoding <string> The character encoding to use. Default: 'utf8'.

  • start <integer> 开始解码的字节偏移量。默认值:0

    start <integer> The byte offset to start decoding at. Default: 0.

  • end <integer> 停止解码的字节偏移量(不包括在内)。默认值:buf.length

    end <integer> The byte offset to stop decoding at (not inclusive). Default: buf.length.

  • 返回:<string>

    Returns: <string>

根据 encoding 中指定的字符编码将 buf 解码为字符串。startend 可以传入仅解码 buf 的子集。

Decodes buf to a string according to the specified character encoding in encoding. start and end may be passed to decode only a subset of buf.

如果 encoding'utf8' 并且输入中的字节序列不是有效的 UTF-8,则每个无效字节都将替换为替换字符 U+FFFD

If encoding is 'utf8' and a byte sequence in the input is not valid UTF-8, then each invalid byte is replaced with the replacement character U+FFFD.

字符串实例(以 UTF-16 代码单元表示)的最大长度可用作 buffer.constants.MAX_STRING_LENGTH

The maximum length of a string instance (in UTF-16 code units) is available as buffer.constants.MAX_STRING_LENGTH.

import { Buffer } from 'node:buffer';

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

console.log(buf1.toString('utf8'));
// Prints: abcdefghijklmnopqrstuvwxyz
console.log(buf1.toString('utf8', 0, 5));
// Prints: abcde

const buf2 = Buffer.from('tést');

console.log(buf2.toString('hex'));
// Prints: 74c3a97374
console.log(buf2.toString('utf8', 0, 3));
// Prints: té
console.log(buf2.toString(undefined, 0, 3));
// Prints: téconst { Buffer } = require('node:buffer');

const buf1 = Buffer.allocUnsafe(26);

for (let i = 0; i < 26; i++) {
  // 97 is the decimal ASCII value for 'a'.
  buf1[i] = i + 97;
}

console.log(buf1.toString('utf8'));
// Prints: abcdefghijklmnopqrstuvwxyz
console.log(buf1.toString('utf8', 0, 5));
// Prints: abcde

const buf2 = Buffer.from('tést');

console.log(buf2.toString('hex'));
// Prints: 74c3a97374
console.log(buf2.toString('utf8', 0, 3));
// Prints: té
console.log(buf2.toString(undefined, 0, 3));
// Prints: té

buf.values()#

buf 值(字节)创建并返回 迭代器。当在 for..of 语句中使用 Buffer 时,会自动调用此函数。

Creates and returns an iterator for buf values (bytes). This function is called automatically when a Buffer is used in a for..of statement.

import { Buffer } from 'node:buffer';

const buf = Buffer.from('buffer');

for (const value of buf.values()) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

for (const value of buf) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114const { Buffer } = require('node:buffer');

const buf = Buffer.from('buffer');

for (const value of buf.values()) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

for (const value of buf) {
  console.log(value);
}
// Prints:
//   98
//   117
//   102
//   102
//   101
//   114

buf.write(string[, offset[, length]][, encoding])#

  • string <string> 要写入 buf 的字符串。

    string <string> String to write to buf.

  • offset <integer> 开始写入 string 之前要跳过的字节数。默认值:0

    offset <integer> Number of bytes to skip before starting to write string. Default: 0.

  • length <integer> 要写入的最大字节数(写入的字节数不会超过 buf.length - offset)。默认值:buf.length - offset

    length <integer> Maximum number of bytes to write (written bytes will not exceed buf.length - offset). Default: buf.length - offset.

  • encoding <string> string 的字符编码。默认值:'utf8'

    encoding <string> The character encoding of string. Default: 'utf8'.

  • 返回:<integer> 写入的字节数。

    Returns: <integer> Number of bytes written.

根据 encoding 中的字符编码将 string 写入 bufoffset 处。length 参数是要写入的字节数。如果 buf 没有足够的空间来容纳整个字符串,则只会写入 string 的一部分。但是,不会写入部分编码的字符。

Writes string to buf at offset according to the character encoding in encoding. The length parameter is the number of bytes to write. If buf did not contain enough space to fit the entire string, only part of string will be written. However, partially encoded characters will not be written.

import { Buffer } from 'node:buffer';

const buf = Buffer.alloc(256);

const len = buf.write('\u00bd + \u00bc = \u00be', 0);

console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
// Prints: 12 bytes: ½ + ¼ = ¾

const buffer = Buffer.alloc(10);

const length = buffer.write('abcd', 8);

console.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : abconst { Buffer } = require('node:buffer');

const buf = Buffer.alloc(256);

const len = buf.write('\u00bd + \u00bc = \u00be', 0);

console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
// Prints: 12 bytes: ½ + ¼ = ¾

const buffer = Buffer.alloc(10);

const length = buffer.write('abcd', 8);

console.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : ab

buf.writeBigInt64BE(value[, offset])#

  • value <bigint> 要写入 buf 的数字。

    value <bigint> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offset

Writes value to buf at the specified offset as big-endian.

value 被解释和写入为二进制补码有符号整数。

value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64BE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04 05 06 07 08>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64BE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04 05 06 07 08>

buf.writeBigInt64LE(value[, offset])#

  • value <bigint> 要写入 buf 的数字。

    value <bigint> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offset

Writes value to buf at the specified offset as little-endian.

value 被解释和写入为二进制补码有符号整数。

value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64LE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05 04 03 02 01>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeBigInt64LE(0x0102030405060708n, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05 04 03 02 01>

buf.writeBigUInt64BE(value[, offset])#

  • value <bigint> 要写入 buf 的数字。

    value <bigint> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offset

Writes value to buf at the specified offset as big-endian.

此函数也可在 writeBigUint64BE 别名下使用。

This function is also available under the writeBigUint64BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64BE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de ca fa fe ca ce fa de>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64BE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de ca fa fe ca ce fa de>

buf.writeBigUInt64LE(value[, offset])#

  • value <bigint> 要写入 buf 的数字。

    value <bigint> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足:0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy: 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offset

Writes value to buf at the specified offset as little-endian

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64LE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de fa ce ca fe fa ca de>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeBigUInt64LE(0xdecafafecacefaden, 0);

console.log(buf);
// Prints: <Buffer de fa ce ca fe fa ca de>

此函数也可在 writeBigUint64LE 别名下使用。

This function is also available under the writeBigUint64LE alias.

buf.writeDoubleBE(value[, offset])#

  • value <number> 要写入 buf 的数字。

    value <number> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offsetvalue 必须是 JavaScript 数字当 value 不是 JavaScript 数字时,则行为未定义。

Writes value to buf at the specified offset as big-endian. The value must be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleBE(123.456, 0);

console.log(buf);
// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleBE(123.456, 0);

console.log(buf);
// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>

buf.writeDoubleLE(value[, offset])#

  • value <number> 要写入 buf 的数字。

    value <number> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 8。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 8. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offsetvalue 必须是 JavaScript 数字当 value 不是 JavaScript 数字时,则行为未定义。

Writes value to buf at the specified offset as little-endian. The value must be a JavaScript number. Behavior is undefined when value is anything other than a JavaScript number.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleLE(123.456, 0);

console.log(buf);
// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(8);

buf.writeDoubleLE(123.456, 0);

console.log(buf);
// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>

buf.writeFloatBE(value[, offset])#

  • value <number> 要写入 buf 的数字。

    value <number> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offset。当 value 不是 JavaScript 数字时,则行为未定义。

Writes value to buf at the specified offset as big-endian. Behavior is undefined when value is anything other than a JavaScript number.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatBE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer 4f 4a fe bb>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeFloatBE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer 4f 4a fe bb>

buf.writeFloatLE(value[, offset])#

  • value <number> 要写入 buf 的数字。

    value <number> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offset。当 value 不是 JavaScript 数字时,则行为未定义。

Writes value to buf at the specified offset as little-endian. Behavior is undefined when value is anything other than a JavaScript number.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeFloatLE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer bb fe 4a 4f>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeFloatLE(0xcafebabe, 0);

console.log(buf);
// Prints: <Buffer bb fe 4a 4f>

buf.writeInt8(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 1。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 写入 buf 中指定的 offsetvalue 必须是有效的有符号 8 位整数。当 value 不是有符号的 8 位整数时,则行为未定义。

Writes value to buf at the specified offset. value must be a valid signed 8-bit integer. Behavior is undefined when value is anything other than a signed 8-bit integer.

value 被解释和写入为二进制补码有符号整数。

value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt8(2, 0);
buf.writeInt8(-2, 1);

console.log(buf);
// Prints: <Buffer 02 fe>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(2);

buf.writeInt8(2, 0);
buf.writeInt8(-2, 1);

console.log(buf);
// Prints: <Buffer 02 fe>

buf.writeInt16BE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offsetvalue 必须是有效的有符号 16 位整数。当 value 不是有符号的 16 位整数时,则行为未定义。

Writes value to buf at the specified offset as big-endian. The value must be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

value 被解释和写入为二进制补码有符号整数。

The value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16BE(0x0102, 0);

console.log(buf);
// Prints: <Buffer 01 02>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(2);

buf.writeInt16BE(0x0102, 0);

console.log(buf);
// Prints: <Buffer 01 02>

buf.writeInt16LE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offsetvalue 必须是有效的有符号 16 位整数。当 value 不是有符号的 16 位整数时,则行为未定义。

Writes value to buf at the specified offset as little-endian. The value must be a valid signed 16-bit integer. Behavior is undefined when value is anything other than a signed 16-bit integer.

value 被解释和写入为二进制补码有符号整数。

The value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(2);

buf.writeInt16LE(0x0304, 0);

console.log(buf);
// Prints: <Buffer 04 03>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(2);

buf.writeInt16LE(0x0304, 0);

console.log(buf);
// Prints: <Buffer 04 03>

buf.writeInt32BE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offsetvalue 必须是有效的有符号 32 位整数。当 value 不是有符号的 32 位整数时,则行为未定义。

Writes value to buf at the specified offset as big-endian. The value must be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

value 被解释和写入为二进制补码有符号整数。

The value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32BE(0x01020304, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeInt32BE(0x01020304, 0);

console.log(buf);
// Prints: <Buffer 01 02 03 04>

buf.writeInt32LE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offsetvalue 必须是有效的有符号 32 位整数。当 value 不是有符号的 32 位整数时,则行为未定义。

Writes value to buf at the specified offset as little-endian. The value must be a valid signed 32-bit integer. Behavior is undefined when value is anything other than a signed 32-bit integer.

value 被解释和写入为二进制补码有符号整数。

The value is interpreted and written as a two's complement signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeInt32LE(0x05060708, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeInt32LE(0x05060708, 0);

console.log(buf);
// Prints: <Buffer 08 07 06 05>

buf.writeIntBE(value, offset, byteLength)#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要写入的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to write. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

valuebyteLength 个字节作为大端序写入 buf 中指定的 offset。支持最高 48 位的精度。当 value 不是有符号整数时,则行为未定义。

Writes byteLength bytes of value to buf at the specified offset as big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than a signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(6);

buf.writeIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>

buf.writeIntLE(value, offset, byteLength)#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要写入的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to write. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

valuebyteLength 个字节作为小端序写入 buf 中指定的 offset。支持最高 48 位的精度。当 value 不是有符号整数时,则行为未定义。

Writes byteLength bytes of value to buf at the specified offset as little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than a signed integer.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(6);

buf.writeIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>

buf.writeUInt8(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 1。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 1. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 写入 buf 中指定的 offsetvalue 必须是有效的无符号 8 位整数。当 value 不是无符号 8 位整数时,则行为未定义。

Writes value to buf at the specified offset. value must be a valid unsigned 8-bit integer. Behavior is undefined when value is anything other than an unsigned 8-bit integer.

此函数也可在 writeUint8 别名下使用。

This function is also available under the writeUint8 alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);

console.log(buf);
// Prints: <Buffer 03 04 23 42>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeUInt8(0x3, 0);
buf.writeUInt8(0x4, 1);
buf.writeUInt8(0x23, 2);
buf.writeUInt8(0x42, 3);

console.log(buf);
// Prints: <Buffer 03 04 23 42>

buf.writeUInt16BE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offsetvalue 必须是有效的无符号 16 位整数。当 value 不是无符号 16 位整数时,则行为未定义。

Writes value to buf at the specified offset as big-endian. The value must be a valid unsigned 16-bit integer. Behavior is undefined when value is anything other than an unsigned 16-bit integer.

此函数也可在 writeUint16BE 别名下使用。

This function is also available under the writeUint16BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer de ad be ef>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16BE(0xdead, 0);
buf.writeUInt16BE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer de ad be ef>

buf.writeUInt16LE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 2。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 2. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offsetvalue 必须是有效的无符号 16 位整数。当 value 不是无符号 16 位整数时,则行为未定义。

Writes value to buf at the specified offset as little-endian. The value must be a valid unsigned 16-bit integer. Behavior is undefined when value is anything other than an unsigned 16-bit integer.

此函数也可在 writeUint16LE 别名下使用。

This function is also available under the writeUint16LE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer ad de ef be>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeUInt16LE(0xdead, 0);
buf.writeUInt16LE(0xbeef, 2);

console.log(buf);
// Prints: <Buffer ad de ef be>

buf.writeUInt32BE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为大端序写入 buf 中指定的 offsetvalue 必须是有效的无符号 32 位整数。当 value 不是无符号 32 位整数时,则行为未定义。

Writes value to buf at the specified offset as big-endian. The value must be a valid unsigned 32-bit integer. Behavior is undefined when value is anything other than an unsigned 32-bit integer.

此函数也可在 writeUint32BE 别名下使用。

This function is also available under the writeUint32BE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32BE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer fe ed fa ce>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32BE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer fe ed fa ce>

buf.writeUInt32LE(value[, offset])#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - 4。默认值:0

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - 4. Default: 0.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

value 作为小端序写入 buf 中指定的 offsetvalue 必须是有效的无符号 32 位整数。当 value 不是无符号 32 位整数时,则行为未定义。

Writes value to buf at the specified offset as little-endian. The value must be a valid unsigned 32-bit integer. Behavior is undefined when value is anything other than an unsigned 32-bit integer.

此函数也可在 writeUint32LE 别名下使用。

This function is also available under the writeUint32LE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32LE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer ce fa ed fe>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(4);

buf.writeUInt32LE(0xfeedface, 0);

console.log(buf);
// Prints: <Buffer ce fa ed fe>

buf.writeUIntBE(value, offset, byteLength)#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要写入的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to write. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

valuebyteLength 个字节作为大端序写入 buf 中指定的 offset。支持最高 48 位的精度。当 value 不是无符号整数时,则行为未定义。

Writes byteLength bytes of value to buf at the specified offset as big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

此函数也可在 writeUintBE 别名下使用。

This function is also available under the writeUintBE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(6);

buf.writeUIntBE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer 12 34 56 78 90 ab>

buf.writeUIntLE(value, offset, byteLength)#

  • value <integer> 要写入 buf 的数字。

    value <integer> Number to be written to buf.

  • offset <integer> 开始写入之前要跳过的字节数。必须满足 0 <= offset <= buf.length - byteLength

    offset <integer> Number of bytes to skip before starting to write. Must satisfy 0 <= offset <= buf.length - byteLength.

  • byteLength <integer> 要写入的字节数。必须满足 0 < byteLength <= 6

    byteLength <integer> Number of bytes to write. Must satisfy 0 < byteLength <= 6.

  • 返回:<integer> offset 加上写入的字节数。

    Returns: <integer> offset plus the number of bytes written.

valuebyteLength 个字节作为小端序写入 buf 中指定的 offset。支持最高 48 位的精度。当 value 不是无符号整数时,则行为未定义。

Writes byteLength bytes of value to buf at the specified offset as little-endian. Supports up to 48 bits of accuracy. Behavior is undefined when value is anything other than an unsigned integer.

此函数也可在 writeUintLE 别名下使用。

This function is also available under the writeUintLE alias.

import { Buffer } from 'node:buffer';

const buf = Buffer.allocUnsafe(6);

buf.writeUIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>const { Buffer } = require('node:buffer');

const buf = Buffer.allocUnsafe(6);

buf.writeUIntLE(0x1234567890ab, 0, 6);

console.log(buf);
// Prints: <Buffer ab 90 78 56 34 12>

new Buffer(array)#

稳定性: 0 - 已弃用:改用 Buffer.from(array)

Stability: 0 - Deprecated: Use Buffer.from(array) instead.

参见 Buffer.from(array)

See Buffer.from(array).

new Buffer(arrayBuffer[, byteOffset[, length]])#

参见 Buffer.from(arrayBuffer[, byteOffset[, length]])

See Buffer.from(arrayBuffer[, byteOffset[, length]]).

new Buffer(buffer)#

稳定性: 0 - 已弃用:改用 Buffer.from(buffer)

Stability: 0 - Deprecated: Use Buffer.from(buffer) instead.

参见 Buffer.from(buffer)

See Buffer.from(buffer).

new Buffer(size)#

稳定性: 0 - 已弃用:请改用 Buffer.alloc()(另请参阅 Buffer.allocUnsafe())。

Stability: 0 - Deprecated: Use Buffer.alloc() instead (also see Buffer.allocUnsafe()).

  • size <integer> 新的 Buffer 所需的长度。

    size <integer> The desired length of the new Buffer.

参见 Buffer.alloc()Buffer.allocUnsafe()。构造函数的此变体等效于 Buffer.alloc()

See Buffer.alloc() and Buffer.allocUnsafe(). This variant of the constructor is equivalent to Buffer.alloc().

new Buffer(string[, encoding])#

稳定性: 0 - 已弃用:改用 Buffer.from(string[, encoding])

Stability: 0 - Deprecated: Use Buffer.from(string[, encoding]) instead.

  • string <string> 要编码的字符串。

    string <string> String to encode.

  • encoding <string> string 的编码。默认值:'utf8'

    encoding <string> The encoding of string. Default: 'utf8'.

参见 Buffer.from(string[, encoding])

See Buffer.from(string[, encoding]).

类:File#

Class: File

File 提供有关文件的信息。

A File provides information about files.

new buffer.File(sources, fileName[, options])#

file.name#

File 的名称。

The name of the File.

file.lastModified#

File 的最后修改日期。

The last modified date of the File.

node:buffer 模块 API#

node:buffer module APIs

虽然 Buffer 对象可作为全局对象使用,但还有其他与 Buffer 相关的 API 仅可通过使用 require('node:buffer') 访问的 node:buffer 模块使用。

While, the Buffer object is available as a global, there are additional Buffer-related APIs that are available only via the node:buffer module accessed using require('node:buffer').

buffer.atob(data)#

稳定性: 3 - 旧版的。改用 Buffer.from(data, 'base64')

Stability: 3 - Legacy. Use Buffer.from(data, 'base64') instead.

  • data <any> Base64 编码的输入字符串。

    data <any> The Base64-encoded input string.

将 Base64 编码的数据字符串解码为字节,并使用 Latin-1 (ISO-8859-1) 将这些字节编码为字符串。

Decodes a string of Base64-encoded data into bytes, and encodes those bytes into a string using Latin-1 (ISO-8859-1).

data 可以是任何可以强制转换为字符串的 JavaScript 值。

The data may be any JavaScript-value that can be coerced into a string.

提供此函数只是为了与旧版 Web 平台 API 兼容,并且永远不应在新代码中使用,因为它们使用字符串来表示二进制数据,并且早于 JavaScript 中类型化数组的引入。对于使用 Node.js API 运行的代码,应使用 Buffer.from(str, 'base64')buf.toString('base64') 执行 Base64 编码字符串和二进制数据之间的转换。

This function is only provided for compatibility with legacy web platform APIs and should never be used in new code, because they use strings to represent binary data and predate the introduction of typed arrays in JavaScript. For code running using Node.js APIs, converting between base64-encoded strings and binary data should be performed using Buffer.from(str, 'base64') and buf.toString('base64').

buffer.btoa(data)#

稳定性: 3 - 旧版的。改用 buf.toString('base64')

Stability: 3 - Legacy. Use buf.toString('base64') instead.

  • data <any> ASCII (Latin1) 字符串。

    data <any> An ASCII (Latin1) string.

使用 Latin-1 (ISO-8859) 将字符串解码为字节,并使用 Base64 将这些字节编码为字符串。

Decodes a string into bytes using Latin-1 (ISO-8859), and encodes those bytes into a string using Base64.

data 可以是任何可以强制转换为字符串的 JavaScript 值。

The data may be any JavaScript-value that can be coerced into a string.

提供此函数只是为了与旧版 Web 平台 API 兼容,并且永远不应在新代码中使用,因为它们使用字符串来表示二进制数据,并且早于 JavaScript 中类型化数组的引入。对于使用 Node.js API 运行的代码,应使用 Buffer.from(str, 'base64')buf.toString('base64') 执行 Base64 编码字符串和二进制数据之间的转换。

This function is only provided for compatibility with legacy web platform APIs and should never be used in new code, because they use strings to represent binary data and predate the introduction of typed arrays in JavaScript. For code running using Node.js APIs, converting between base64-encoded strings and binary data should be performed using Buffer.from(str, 'base64') and buf.toString('base64').

buffer.isAscii(input)#

如果 input 仅包含有效的 ASCII 编码数据,此函数返回 true,包括 input 为空的情况。

This function returns true if input contains only valid ASCII-encoded data, including the case in which input is empty.

如果 input 是分离的数组缓冲区则抛出异常。

Throws if the input is a detached array buffer.

buffer.isUtf8(input)#

如果 input 仅包含有效的 UTF-8 编码数据,此函数返回 true,包括 input 为空的情况。

This function returns true if input contains only valid UTF-8-encoded data, including the case in which input is empty.

如果 input 是分离的数组缓冲区则抛出异常。

Throws if the input is a detached array buffer.

buffer.INSPECT_MAX_BYTES#

返回调用 buf.inspect() 时将返回的最大字节数。这可以被用户模块覆盖。有关 buf.inspect() 行为的更多详细信息,请参阅 util.inspect()

Returns the maximum number of bytes that will be returned when buf.inspect() is called. This can be overridden by user modules. See util.inspect() for more details on buf.inspect() behavior.

buffer.kMaxLength#

  • <integer> 单个 Buffer 实例允许的最大大小。

    <integer> The largest size allowed for a single Buffer instance.

buffer.constants.MAX_LENGTH 的别名。

An alias for buffer.constants.MAX_LENGTH.

buffer.kStringMaxLength#

  • <integer> 单个 string 实例允许的最大长度。

    <integer> The largest length allowed for a single string instance.

buffer.constants.MAX_STRING_LENGTH 的别名。

An alias for buffer.constants.MAX_STRING_LENGTH.

buffer.resolveObjectURL(id)#

稳定性: 1 - 实验性的

Stability: 1 - Experimental

  • id <string> 先前调用 URL.createObjectURL() 返回的 'blob:nodedata:... 网址字符串。

    id <string> A 'blob:nodedata:... URL string returned by a prior call to URL.createObjectURL().

  • 返回:<Blob>

    Returns: <Blob>

解析 'blob:nodedata:...',关联的使用先前调用 URL.createObjectURL() 注册的 <Blob> 对象。

Resolves a 'blob:nodedata:...' an associated <Blob> object registered using a prior call to URL.createObjectURL().

buffer.transcode(source, fromEnc, toEnc)#

将给定的 BufferUint8Array 实例从一种字符编码重新编码为另一种。返回新的 Buffer 实例。

Re-encodes the given Buffer or Uint8Array instance from one character encoding to another. Returns a new Buffer instance.

如果 fromEnctoEnc 指定无效的字符编码或不允许从 fromEnc 转换为 toEnc,则抛出错误。

Throws if the fromEnc or toEnc specify invalid character encodings or if conversion from fromEnc to toEnc is not permitted.

buffer.transcode() 支持的编码有:'ascii''utf8''utf16le''ucs2''latin1''binary'

Encodings supported by buffer.transcode() are: 'ascii', 'utf8', 'utf16le', 'ucs2', 'latin1', and 'binary'.

如果给定的字节序列不能在目标编码中充分表示,则转码过程将使用替换字符。例如:

The transcoding process will use substitution characters if a given byte sequence cannot be adequately represented in the target encoding. For instance:

import { Buffer, transcode } from 'node:buffer';

const newBuf = transcode(Buffer.from('€'), 'utf8', 'ascii');
console.log(newBuf.toString('ascii'));
// Prints: '?'const { Buffer, transcode } = require('node:buffer');

const newBuf = transcode(Buffer.from('€'), 'utf8', 'ascii');
console.log(newBuf.toString('ascii'));
// Prints: '?'

由于欧元 () 符号在 US-ASCII 中无法表示,因此在转码后的 Buffer 中将其替换为 ?

Because the Euro () sign is not representable in US-ASCII, it is replaced with ? in the transcoded Buffer.

类:SlowBuffer#

Class: SlowBuffer

稳定性: 0 - 已弃用:改用 Buffer.allocUnsafeSlow()

Stability: 0 - Deprecated: Use Buffer.allocUnsafeSlow() instead.

参见 Buffer.allocUnsafeSlow()。从构造函数总是返回 Buffer 实例而不是 SlowBuffer 实例的意义上来说,这从来都不是一个类。

See Buffer.allocUnsafeSlow(). This was never a class in the sense that the constructor always returned a Buffer instance, rather than a SlowBuffer instance.

new SlowBuffer(size)#

稳定性: 0 - 已弃用:改用 Buffer.allocUnsafeSlow()

Stability: 0 - Deprecated: Use Buffer.allocUnsafeSlow() instead.

  • size <integer> 新的 SlowBuffer 所需的长度。

    size <integer> The desired length of the new SlowBuffer.

参见 Buffer.allocUnsafeSlow()

See Buffer.allocUnsafeSlow().

缓冲区常量#

Buffer constants

buffer.constants.MAX_LENGTH#
  • <integer> 单个 Buffer 实例允许的最大大小。

    <integer> The largest size allowed for a single Buffer instance.

在 32 位架构上,该值当前为 230 - 1(约 1 GiB)。

On 32-bit architectures, this value currently is 230 - 1 (about 1 GiB).

在 64 位架构上,该值当前为 232(大约 4 GiB)。

On 64-bit architectures, this value currently is 232 (about 4 GiB).

它反映了引擎盖下的 v8::TypedArray::kMaxLength

It reflects v8::TypedArray::kMaxLength under the hood.

此值也可用作 buffer.kMaxLength

This value is also available as buffer.kMaxLength.

buffer.constants.MAX_STRING_LENGTH#
  • <integer> 单个 string 实例允许的最大长度。

    <integer> The largest length allowed for a single string instance.

表示 string 基础类型可以拥有的最大 length,以 UTF-16 代码单元计算。

Represents the largest length that a string primitive can have, counted in UTF-16 code units.

此值可能取决于正在使用的 JS 引擎。

This value may depend on the JS engine that is being used.

Buffer.from()Buffer.alloc()Buffer.allocUnsafe()#

Buffer.from(), Buffer.alloc(), and Buffer.allocUnsafe()

在 Node.js 6.0.0 之前的版本中,Buffer 实例是使用 Buffer 构造函数创建的,它根据提供的参数以不同的方式分配返回的 Buffer

In versions of Node.js prior to 6.0.0, Buffer instances were created using the Buffer constructor function, which allocates the returned Buffer differently based on what arguments are provided:

  • 将数字作为第一个参数传给 Buffer()(例如 new Buffer(10))会分配指定大小的新 Buffer 对象。在 Node.js 8.0.0 之前,为此类 Buffer 实例分配的内存未初始化,并且可能包含敏感数据。此类 Buffer 实例随后必须通过使用 buf.fill(0) 或在从 Buffer 读取数据之前写入整个 Buffer 来初始化。虽然这种行为是为了提高性能,但开发经验表明,创建快速但未初始化的 Buffer 与创建速度较慢但更安全的 Buffer 之间需要更明确的区别。从 Node.js 8.0.0 开始,Buffer(num)new Buffer(num) 返回带有初始化内存的 Buffer

    Passing a number as the first argument to Buffer() (e.g. new Buffer(10)) allocates a new Buffer object of the specified size. Prior to Node.js 8.0.0, the memory allocated for such Buffer instances is not initialized and can contain sensitive data. Such Buffer instances must be subsequently initialized by using either buf.fill(0) or by writing to the entire Buffer before reading data from the Buffer. While this behavior is intentional to improve performance, development experience has demonstrated that a more explicit distinction is required between creating a fast-but-uninitialized Buffer versus creating a slower-but-safer Buffer. Since Node.js 8.0.0, Buffer(num) and new Buffer(num) return a Buffer with initialized memory.

  • 传入字符串、数组或 Buffer 作为第一个参数会将传入的对象的数据复制到 Buffer

    Passing a string, array, or Buffer as the first argument copies the passed object's data into the Buffer.

  • 传入 ArrayBufferSharedArrayBuffer 返回 Buffer,它与给定的数组缓冲区共享分配的内存。

    Passing an ArrayBuffer or a SharedArrayBuffer returns a Buffer that shares allocated memory with the given array buffer.

由于 new Buffer() 的行为因第一个参数的类型而异,因此当未执行参数验证或 Buffer 初始化时,可能会无意中将安全性和可靠性问题引入到应用中。

Because the behavior of new Buffer() is different depending on the type of the first argument, security and reliability issues can be inadvertently introduced into applications when argument validation or Buffer initialization is not performed.

例如,如果攻击者可以使应用接收到预期为字符串的数字,则应用可能会调用 new Buffer(100) 而不是 new Buffer("100"),从而导致它分配 100 字节的缓冲区,而不是分配内容为 "100" 的 3 字节缓冲区。这通常可以使用 JSON API 调用实现。由于 JSON 区分数字和字符串类型,因此它允许在未充分验证其输入的天真编写的应用可能期望始终接收字符串的情况下注入数字。在 Node.js 8.0.0 之前,100 字节的缓冲区可能包含任意预先存在的内存数据,因此可用于向远程攻击者公开内存秘密。从 Node.js 8.0.0 开始,不会发生内存暴露,因为数据是零填充的。但是,其他攻击仍然是可能的,例如导致服务器分配非常大的缓冲区,导致性能下降或因内存耗尽而崩溃。

For example, if an attacker can cause an application to receive a number where a string is expected, the application may call new Buffer(100) instead of new Buffer("100"), leading it to allocate a 100 byte buffer instead of allocating a 3 byte buffer with content "100". This is commonly possible using JSON API calls. Since JSON distinguishes between numeric and string types, it allows injection of numbers where a naively written application that does not validate its input sufficiently might expect to always receive a string. Before Node.js 8.0.0, the 100 byte buffer might contain arbitrary pre-existing in-memory data, so may be used to expose in-memory secrets to a remote attacker. Since Node.js 8.0.0, exposure of memory cannot occur because the data is zero-filled. However, other attacks are still possible, such as causing very large buffers to be allocated by the server, leading to performance degradation or crashing on memory exhaustion.

为了使 Buffer 实例的创建更加可靠且不易出错,各种形式的 new Buffer() 构造函数已被弃用,并由单独的 Buffer.from()Buffer.alloc()Buffer.allocUnsafe() 方法替代。

To make the creation of Buffer instances more reliable and less error-prone, the various forms of the new Buffer() constructor have been deprecated and replaced by separate Buffer.from(), Buffer.alloc(), and Buffer.allocUnsafe() methods.

开发者应将 new Buffer() 构造函数的所有现有用途迁移到这些新 API 之一。

Developers should migrate all existing uses of the new Buffer() constructors to one of these new APIs.

如果 size 小于或等于 Buffer.poolSize 的一半,则 Buffer.allocUnsafe()Buffer.from(array) 返回的 Buffer 实例可以从共享内部内存池中分配。Buffer.allocUnsafeSlow() 返回的实例从不使用共享内部内存池。

Buffer instances returned by Buffer.allocUnsafe() and Buffer.from(array) may be allocated off a shared internal memory pool if size is less than or equal to half Buffer.poolSize. Instances returned by Buffer.allocUnsafeSlow() never use the shared internal memory pool.

--zero-fill-buffers 命令行选项#

The --zero-fill-buffers command-line option

可以使用 --zero-fill-buffers 命令行选项启动 Node.js,使所有新分配的 Buffer 实例在创建时默认为零填充。如果没有该选项,则使用 Buffer.allocUnsafe()Buffer.allocUnsafeSlow()new SlowBuffer(size) 创建的缓冲区不会被零填充。使用此标志会对性能产生可衡量的负面影响。仅在必要时使用 --zero-fill-buffers 选项以强制新分配的 Buffer 实例不能包含可能敏感的旧数据。

Node.js can be started using the --zero-fill-buffers command-line option to cause all newly-allocated Buffer instances to be zero-filled upon creation by default. Without the option, buffers created with Buffer.allocUnsafe(), Buffer.allocUnsafeSlow(), and new SlowBuffer(size) are not zero-filled. Use of this flag can have a measurable negative impact on performance. Use the --zero-fill-buffers option only when necessary to enforce that newly allocated Buffer instances cannot contain old data that is potentially sensitive.

$ node --zero-fill-buffers
> Buffer.allocUnsafe(5);
<Buffer 00 00 00 00 00> 

是什么让 Buffer.allocUnsafe()Buffer.allocUnsafeSlow() "不安全"?#

What makes Buffer.allocUnsafe() and Buffer.allocUnsafeSlow() "unsafe"?

调用 Buffer.allocUnsafe()Buffer.allocUnsafeSlow() 时,分配的内存段未初始化(未清零)。虽然这种设计使内存分配速度非常快,但分配的内存段可能包含可能敏感的旧数据。使用由 Buffer.allocUnsafe() 创建的 Buffer 而没有完全覆盖内存可以让旧数据在读取 Buffer 内存时泄漏。

When calling Buffer.allocUnsafe() and Buffer.allocUnsafeSlow(), the segment of allocated memory is uninitialized (it is not zeroed-out). While this design makes the allocation of memory quite fast, the allocated segment of memory might contain old data that is potentially sensitive. Using a Buffer created by Buffer.allocUnsafe() without completely overwriting the memory can allow this old data to be leaked when the Buffer memory is read.

虽然使用 Buffer.allocUnsafe() 有明显的性能优势,但必须格外小心以避免将安全漏洞引入应用。

While there are clear performance advantages to using Buffer.allocUnsafe(), extra care must be taken in order to avoid introducing security vulnerabilities into an application.