- assert 断言
- async_hooks 异步钩子
- async_hooks/context 异步上下文
- buffer 缓冲区
- C++插件
- C/C++插件(使用 Node-API)
- C++嵌入器
- child_process 子进程
- cluster 集群
- CLI 命令行
- console 控制台
- Corepack 核心包
- crypto 加密
- crypto/webcrypto 网络加密
- debugger 调试器
- deprecation 弃用
- dgram 数据报
- diagnostics_channel 诊断通道
- dns 域名服务器
- domain 域
- Error 错误
- events 事件触发器
- fs 文件系统
- global 全局变量
- http 超文本传输协议
- http2 超文本传输协议 2.0
- https 安全超文本传输协议
- inspector 检查器
- Intl 国际化
- module 模块
- module/cjs CommonJS 模块
- module/esm ECMAScript 模块
- module/package 包模块
- module/typescript TS 模块
- net 网络
- os 操作系统
- path 路径
- perf_hooks 性能钩子
- permission 权限
- process 进程
- punycode 域名代码
- querystring 查询字符串
- readline 逐行读取
- repl 交互式解释器
- report 诊断报告
- sea 单个可执行应用程序
Node.js v22.11.0 文档
- Node.js v22.11.0
-
目录
- 缓冲区
- 缓冲区和字符编码
- 缓冲区和 TypedArray
- 缓冲区和迭代
- 类:
Blob
- 类:
Buffer
- 静态方法:
Buffer.alloc(size[, fill[, encoding]])
- 静态方法:
Buffer.allocUnsafe(size)
- 静态方法:
Buffer.allocUnsafeSlow(size)
- 静态方法:
Buffer.byteLength(string[, encoding])
- 静态方法:
Buffer.compare(buf1, buf2)
- 静态方法:
Buffer.concat(list[, totalLength])
- 静态方法:
Buffer.copyBytesFrom(view[, offset[, length]])
- 静态方法:
Buffer.from(array)
- 静态方法:
Buffer.from(arrayBuffer[, byteOffset[, length]])
- 静态方法:
Buffer.from(buffer)
- 静态方法:
Buffer.from(object[, offsetOrEncoding[, length]])
- 静态方法:
Buffer.from(string[, encoding])
- 静态方法:
Buffer.isBuffer(obj)
- 静态方法:
Buffer.isEncoding(encoding)
- 类属性:
Buffer.poolSize
buf[index]
buf.buffer
buf.byteOffset
buf.compare(target[, targetStart[, targetEnd[, sourceStart[, sourceEnd]]]])
buf.copy(target[, targetStart[, sourceStart[, sourceEnd]]])
buf.entries()
buf.equals(otherBuffer)
buf.fill(value[, offset[, end]][, encoding])
buf.includes(value[, byteOffset][, encoding])
buf.indexOf(value[, byteOffset][, encoding])
buf.keys()
buf.lastIndexOf(value[, byteOffset][, encoding])
buf.length
buf.parent
buf.readBigInt64BE([offset])
buf.readBigInt64LE([offset])
buf.readBigUInt64BE([offset])
buf.readBigUInt64LE([offset])
buf.readDoubleBE([offset])
buf.readDoubleLE([offset])
buf.readFloatBE([offset])
buf.readFloatLE([offset])
buf.readInt8([offset])
buf.readInt16BE([offset])
buf.readInt16LE([offset])
buf.readInt32BE([offset])
buf.readInt32LE([offset])
buf.readIntBE(offset, byteLength)
buf.readIntLE(offset, byteLength)
buf.readUInt8([offset])
buf.readUInt16BE([offset])
buf.readUInt16LE([offset])
buf.readUInt32BE([offset])
buf.readUInt32LE([offset])
buf.readUIntBE(offset, byteLength)
buf.readUIntLE(offset, byteLength)
buf.subarray([start[, end]])
buf.slice([start[, end]])
buf.swap16()
buf.swap32()
buf.swap64()
buf.toJSON()
buf.toString([encoding[, start[, end]]])
buf.values()
buf.write(string[, offset[, length]][, encoding])
buf.writeBigInt64BE(value[, offset])
buf.writeBigInt64LE(value[, offset])
buf.writeBigUInt64BE(value[, offset])
buf.writeBigUInt64LE(value[, offset])
buf.writeDoubleBE(value[, offset])
buf.writeDoubleLE(value[, offset])
buf.writeFloatBE(value[, offset])
buf.writeFloatLE(value[, offset])
buf.writeInt8(value[, offset])
buf.writeInt16BE(value[, offset])
buf.writeInt16LE(value[, offset])
buf.writeInt32BE(value[, offset])
buf.writeInt32LE(value[, offset])
buf.writeIntBE(value, offset, byteLength)
buf.writeIntLE(value, offset, byteLength)
buf.writeUInt8(value[, offset])
buf.writeUInt16BE(value[, offset])
buf.writeUInt16LE(value[, offset])
buf.writeUInt32BE(value[, offset])
buf.writeUInt32LE(value[, offset])
buf.writeUIntBE(value, offset, byteLength)
buf.writeUIntLE(value, offset, byteLength)
new Buffer(array)
new Buffer(arrayBuffer[, byteOffset[, length]])
new Buffer(buffer)
new Buffer(size)
new Buffer(string[, encoding])
- 静态方法:
- 类:
File
node:buffer
模块 APIBuffer.from()
、Buffer.alloc()
和Buffer.allocUnsafe()
- 缓冲区
-
导航
- assert 断言
- async_hooks 异步钩子
- async_hooks/context 异步上下文
- buffer 缓冲区
- C++插件
- C/C++插件(使用 Node-API)
- C++嵌入器
- child_process 子进程
- cluster 集群
- CLI 命令行
- console 控制台
- Corepack 核心包
- crypto 加密
- crypto/webcrypto 网络加密
- debugger 调试器
- deprecation 弃用
- dgram 数据报
- diagnostics_channel 诊断通道
- dns 域名服务器
- domain 域
- Error 错误
- events 事件触发器
- fs 文件系统
- global 全局变量
- http 超文本传输协议
- http2 超文本传输协议 2.0
- https 安全超文本传输协议
- inspector 检查器
- Intl 国际化
- module 模块
- module/cjs CommonJS 模块
- module/esm ECMAScript 模块
- module/package 包模块
- module/typescript TS 模块
- net 网络
- os 操作系统
- path 路径
- perf_hooks 性能钩子
- permission 权限
- process 进程
- punycode 域名代码
- querystring 查询字符串
- readline 逐行读取
- repl 交互式解释器
- report 诊断报告
- sea 单个可执行应用程序
- 其他版本
缓冲区#
¥Buffer
¥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 Buffer
s.
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 Uint8Array
s wherever Buffer
s 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
在 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 Buffer
s 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'
或 '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 aBuffer
into a string that does not exclusively contain valid UTF-8 data, the Unicode replacement characterU+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-16 的 little-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+0000
至U+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 fromU+0000
toU+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 aBuffer
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 aBuffer
from a string, this encoding will also correctly accept regular base64-encoded strings. When encoding aBuffer
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 aBuffer
, this is equivalent to using'latin1'
. When decoding aBuffer
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 andBuffer
s, 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'
和 '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 Uint8Array
和 TypedArray
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 Buffer
s. There are,
however, subtle incompatibilities between the Buffer
API and the
TypedArray
API.
特别是:
¥In particular:
-
TypedArray.prototype.slice()
创建TypedArray
部分的副本,而Buffer.prototype.slice()
在现有Buffer
上创建视图而不进行复制。这种行为可能会有意外,并且仅存在于旧版兼容性中。TypedArray.prototype.subarray()
可用于在Buffer
和其他TypedArray
上实现Buffer.prototype.slice()
的行为,应优先使用。¥While
TypedArray.prototype.slice()
creates a copy of part of theTypedArray
,Buffer.prototype.slice()
creates a view over the existingBuffer
without copying. This behavior can be surprising, and only exists for legacy compatibility.TypedArray.prototype.subarray()
can be used to achieve the behavior ofBuffer.prototype.slice()
on bothBuffer
s and otherTypedArray
s and should be preferred. -
buf.toString()
与其对应的TypedArray
不兼容。¥
buf.toString()
is incompatible with itsTypedArray
equivalent. -
多种方法,例如
buf.indexOf()
,支持额外的参数。¥A number of methods, e.g.
buf.indexOf()
, support additional arguments.
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
:
-
将
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 aTypedArray
constructor will copy theBuffer
s 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 ]
-
传递
ArrayBuffer
底层的Buffer
将创建一个与Buffer
共享其内存的TypedArray
。¥Passing the
Buffer
s underlyingArrayBuffer
will create aTypedArray
that shares its memory with theBuffer
.
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 Buffer
。Buffer.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
的 .buffer
创建 Buffer
时,可以通过传入 byteOffset
和 length
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: 16
const { 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()
和 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
// 3
const { 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()
和 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]])
#
-
sources
<string[]> | <ArrayBuffer[]> | <TypedArray[]> | <DataView[]> | <Blob[]> 将存储在Blob
中的字符串数组、<ArrayBuffer>、<TypedArray>、<DataView> 或 <Blob> 对象、或此类对象的任何组合。¥
sources
<string[]> | <ArrayBuffer[]> | <TypedArray[]> | <DataView[]> | <Blob[]> An array of string, <ArrayBuffer>, <TypedArray>, <DataView>, or <Blob> objects, or any mix of such objects, that will be stored within theBlob
. -
options
<Object>-
endings
<string>'transparent'
或'native'
之一。设置为'native'
时,字符串源部分中的行结束将转换为require('node:os').EOL
指定的平台原生行结束。¥
endings
<string> One of either'transparent'
or'native'
. When set to'native'
, line endings in string source parts will be converted to the platform native line-ending as specified byrequire('node:os').EOL
. -
type
<string> Blob 内容类型。type
的目的是传达数据的 MIME 媒体类型,但是不执行类型格式的验证。¥
type
<string> The Blob content-type. The intent is fortype
to convey the MIME media type of the data, however no validation of the type format is performed.
-
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> 和 <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.bytes()
#
blob.bytes()
方法将 Blob
对象的字节作为 Promise<Uint8Array>
返回。
¥The blob.bytes()
method returns the byte of the Blob
object as a Promise<Uint8Array>
.
const blob = new Blob(['hello']);
blob.bytes().then((bytes) => {
console.log(bytes); // Outputs: Uint8Array(5) [ 104, 101, 108, 108, 111 ]
});
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]]])
#
-
start
<number> 起始索引。¥
start
<number> The starting index. -
end
<number> 结束索引。¥
end
<number> The ending index. -
type
<string> 新Blob
的内容类型¥
type
<string> The content-type for the newBlob
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()
#
-
¥Returns: <ReadableStream>
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()
或 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]])
-
size
<integer> 新的Buffer
所需的长度。¥
size
<integer> The desired length of the newBuffer
. -
fill
<string> | <Buffer> | <Uint8Array> | <integer> 用于预填充新Buffer
的值。默认值:0
。¥
fill
<string> | <Buffer> | <Uint8Array> | <integer> A value to pre-fill the newBuffer
with. Default:0
. -
encoding
<string> 如果fill
是字符串,则这就是它的编码。默认值:'utf8'
。¥
encoding
<string> Iffill
is a string, this is its encoding. Default:'utf8'
.
分配 size
个字节的新 Buffer
。如果 fill
为 undefined
,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 fill
和 encoding
,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 Buffer
s.
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)
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,该实例仅当 size
小于 Buffer.poolSize >>> 1
(Buffer.poolSize
的下限除以二)时才用作使用 Buffer.allocUnsafe()
、Buffer.from(array)
、Buffer.from(string)
和 Buffer.concat()
创建的新 Buffer
实例的快速分配池。
¥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)
,
Buffer.from(string)
, 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)
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.
使用 Buffer.allocUnsafe()
分配新的 Buffer
实例时,小于 Buffer.poolSize >>> 1
(使用默认 poolSize 时为 4KiB)的分配将从单个预分配的 Buffer
中切出。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 less than Buffer.poolSize >>> 1
(4KiB when default poolSize is used) 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])
-
string
<string> | <Buffer> | <TypedArray> | <DataView> | <ArrayBuffer> | <SharedArrayBuffer> 用于计算长度的值。¥
string
<string> | <Buffer> | <TypedArray> | <DataView> | <ArrayBuffer> | <SharedArrayBuffer> A value to calculate the length of. -
encoding
<string> 如果string
是字符串,则这就是它的编码。默认值:'utf8'
。¥
encoding
<string> Ifstring
is a string, this is its encoding. Default:'utf8'
. -
返回:<integer>
string
中包含的字节数。¥Returns: <integer> The number of bytes contained within
string
.
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'
和 '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 bytes
const { 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
当 string
为 Buffer
/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)
-
buf1
<Buffer> | <Uint8Array> -
buf2
<Buffer> | <Uint8Array> -
返回:<integer>
-1
、0
或1
,取决于比较的结果。详见buf.compare()
。¥Returns: <integer> Either
-1
,0
, or1
, depending on the result of the comparison. Seebuf.compare()
for details.
比较 buf1
和 buf2
,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])
-
list
<Buffer[]> | <Uint8Array[]> 要连接的Buffer
或Uint8Array
实例的列表。¥
list
<Buffer[]> | <Uint8Array[]> List ofBuffer
orUint8Array
instances to concatenate. -
totalLength
<integer> 连接时list
中Buffer
实例的总长度。¥
totalLength
<integer> Total length of theBuffer
instances inlist
when concatenated. -
返回:<Buffer>
¥Returns: <Buffer>
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 Buffer
s 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: 42
const { 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
<TypedArray> 要复制的 <TypedArray>。¥
view
<TypedArray> The <TypedArray> to copy. -
offset
<integer>view
中的起始偏移量。Default::0
。¥
offset
<integer> The starting offset withinview
. Default::0
. -
length
<integer>view
中要复制的元素数。默认值:view.length - offset
。¥
length
<integer> The number of elements fromview
to copy. Default:view.length - offset
.
将 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)
array
<integer[]>
使用 0
– 255
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 0
– 255
.
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 Buffer
或 Uint8Array
。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)
和 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]])
-
arrayBuffer
<ArrayBuffer> | <SharedArrayBuffer>ArrayBuffer
、SharedArrayBuffer
,例如TypedArray
的.buffer
属性。¥
arrayBuffer
<ArrayBuffer> | <SharedArrayBuffer> AnArrayBuffer
,SharedArrayBuffer
, for example the.buffer
property of aTypedArray
. -
byteOffset
<integer> 要暴露的第一个字节的索引。默认值:0
。¥
byteOffset
<integer> Index of first byte to expose. Default:0
. -
length
<integer> 要暴露的字节数。默认值:arrayBuffer.byteLength - byteOffset
。¥
length
<integer> Number of bytes to expose. Default:arrayBuffer.byteLength - byteOffset
.
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 byteOffset
和 length
参数指定了 arrayBuffer
中将由 Buffer
共享的内存范围。
¥The optional byteOffset
and length
arguments specify a memory range within
the arrayBuffer
that will be shared by the Buffer
.
import { Buffer } from 'node:buffer';
const ab = new ArrayBuffer(10);
const buf = Buffer.from(ab, 0, 2);
console.log(buf.length);
// Prints: 2
const { 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 ArrayBuffer
或 SharedArrayBuffer
或其他适用于 Buffer.from()
变体的类型,则将抛出 TypeError
。
¥A TypeError
will be thrown if arrayBuffer
is not an ArrayBuffer
or a
SharedArrayBuffer
or another type appropriate for Buffer.from()
variants.
记住,支持 ArrayBuffer
可以覆盖超出 TypedArray
视图边界的内存范围。使用 TypedArray
的 buffer
属性创建的新 Buffer
可能会超出 TypedArray
的范围:
¥It is important to remember that a backing ArrayBuffer
can cover a range
of memory that extends beyond the bounds of a TypedArray
view. A new
Buffer
created using the buffer
property of a TypedArray
may extend
beyond the range of the TypedArray
:
import { Buffer } from 'node:buffer';
const arrA = Uint8Array.from([0x63, 0x64, 0x65, 0x66]); // 4 elements
const arrB = new Uint8Array(arrA.buffer, 1, 2); // 2 elements
console.log(arrA.buffer === arrB.buffer); // true
const buf = Buffer.from(arrB.buffer);
console.log(buf);
// Prints: <Buffer 63 64 65 66>
const { Buffer } = require('node:buffer');
const arrA = Uint8Array.from([0x63, 0x64, 0x65, 0x66]); // 4 elements
const arrB = new Uint8Array(arrA.buffer, 1, 2); // 2 elements
console.log(arrA.buffer === arrB.buffer); // true
const buf = Buffer.from(arrB.buffer);
console.log(buf);
// Prints: <Buffer 63 64 65 66>
静态方法:Buffer.from(buffer)
#
¥Static method: Buffer.from(buffer)
-
buffer
<Buffer> | <Uint8Array> 要从中复制数据的现有Buffer
或Uint8Array
。¥
buffer
<Buffer> | <Uint8Array> An existingBuffer
orUint8Array
from which to copy data.
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: buffer
const { 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]])
-
object
<Object> 支持Symbol.toPrimitive
或valueOf()
的对象。¥
object
<Object> An object supportingSymbol.toPrimitive
orvalueOf()
. -
offsetOrEncoding
<integer> | <string> 字节偏移量或编码。¥
offsetOrEncoding
<integer> | <string> A byte-offset or encoding. -
length
<integer> 长度。¥
length
<integer> A 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 ofstring
. Default:'utf8'
.
创建包含 string
的新 Buffer
。encoding
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 tést
const { 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.
Buffer.from(string)
也像 Buffer.allocUnsafe()
一样使用内部 Buffer
池。
¥Buffer.from(string)
may also use the internal Buffer
pool like
Buffer.allocUnsafe()
does.
静态方法:Buffer.isBuffer(obj)
#
¥Static method: Buffer.isBuffer(obj)
如果 obj
是 Buffer
,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)); // false
const { 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)
-
encoding
<string> 要检查的字符编码名称。¥
encoding
<string> A character encoding name to check. -
返回:<boolean>
¥Returns: <boolean>
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: false
const { 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]
#
index
<integer>
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 0x00
和 0xFF
(十六进制)或 0
和 255
(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.length
,buf[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.js
const { 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 thisBuffer
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: true
const { 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 theBuffer
s underlyingArrayBuffer
object.
当在 Buffer.from(ArrayBuffer, byteOffset, length)
中设置 byteOffset
时,或者有时在分配小于 Buffer.poolSize
的 Buffer
时,缓冲区不会从底层 ArrayBuffer
上的零偏移量开始。
¥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buf
的Buffer
或Uint8Array
。¥
target
<Buffer> | <Uint8Array> ABuffer
orUint8Array
with which to comparebuf
. -
targetStart
<integer>target
内开始比较的偏移量。默认值:0
。¥
targetStart
<integer> The offset withintarget
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 withintarget
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 withinbuf
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 withinbuf
at which to end comparison (not inclusive). Default:buf.length
. -
返回:<integer>
¥Returns: <integer>
将 buf
与 target
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
target
与buf
相同,则返回0
¥
0
is returned iftarget
is the same asbuf
-
如果排序时
target
应该在buf
之前,则返回1
。¥
1
is returned iftarget
should come beforebuf
when sorted. -
如果排序时
target
应该在buf
之后,则返回-1
。¥
-1
is returned iftarget
should come afterbuf
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 targetStart
、targetEnd
、sourceStart
和 sourceEnd
参数可用于分别将比较限制在 target
和 buf
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: 1
const { 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 < 0
、sourceStart < 0
、targetEnd > target.byteLength
或 sourceEnd > 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Buffer
或Uint8Array
。¥
target
<Buffer> | <Uint8Array> ABuffer
orUint8Array
to copy into. -
targetStart
<integer>target
内开始写入的偏移量。默认值:0
。¥
targetStart
<integer> The offset withintarget
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 withinbuf
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 withinbuf
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 Buffer
s, 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: efghijghijklmnopqrstuvwxyz
const { 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()
#
-
返回:<Iterator>
¥Returns: <Iterator>
根据 buf
的内容创建并返回 迭代器 对 [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)
#
-
otherBuffer
<Buffer> | <Uint8Array> 用于比较buf
的Buffer
或Uint8Array
。¥
otherBuffer
<Buffer> | <Uint8Array> ABuffer
orUint8Array
with which to comparebuf
. -
返回:<boolean>
¥Returns: <boolean>
如果 buf
和 otherBuffer
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: false
const { 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 fillbuf
. Empty value (string, Uint8Array, Buffer) is coerced to0
. -
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 fillbuf
. 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 fillingbuf
(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 forvalue
ifvalue
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 offset
和 end
,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 inbuf
. If negative, then offset is calculated from the end ofbuf
. 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> Ifvalue
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
ifvalue
was found inbuf
,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: false
const { 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 inbuf
. If negative, then offset is calculated from the end ofbuf
. 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> Ifvalue
is a string, this is the encoding used to determine the binary representation of the string that will be searched for inbuf
. 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
inbuf
, or-1
ifbuf
does not containvalue
.
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 inencoding
. -
Buffer
或Uint8Array
,value
将全部使用。要比较部分Buffer
,则使用buf.subarray
。¥a
Buffer
orUint8Array
,value
will be used in its entirety. To compare a partialBuffer
, usebuf.subarray
. -
数字,
value
将被解释为0
和255
之间的无符号 8 位整数值。¥a number,
value
will be interpreted as an unsigned 8-bit integer value between0
and255
.
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: 6
const { 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 NaN
或 0
,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 Buffer
且 byteOffset
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()
#
-
返回:<Iterator>
¥Returns: <Iterator>
创建并返回 迭代器 个 buf
个键(索引)。
¥Creates and returns an iterator of buf
keys (indexes).
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
// 5
const { 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 inbuf
. If negative, then offset is calculated from the end ofbuf
. 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> Ifvalue
is a string, this is the encoding used to determine the binary representation of the string that will be searched for inbuf
. 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
inbuf
, or-1
ifbuf
does not containvalue
.
与 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: 4
const { 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 {}
或 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: 1234
const { 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
#
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
.
从 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
.
从 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: 4294967295n
const { 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: 18446744069414584320n
const { 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 satisfy0 <= 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-304
const { 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 satisfy0 <= 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 satisfy0 <= 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-38
const { 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 satisfy0 <= 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 satisfy0 <= 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
.
从 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 satisfy0 <= 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
.
从 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: 5
const { 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 satisfy0 <= 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
.
从 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 satisfy0 <= 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
.
从 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: 5
const { 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 satisfy0 <= 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
.
从 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 satisfy0 <= 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 satisfy0 < 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 satisfy0 <= 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 satisfy0 < 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: -546f87a9cbee
const { 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 satisfy0 <= 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 satisfy0 <= 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: 3456
const { 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 satisfy0 <= 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 satisfy0 <= 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: 12345678
const { 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 satisfy0 <= 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 satisfy0 <= 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 satisfy0 < 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 satisfy0 <= 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 satisfy0 < 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: ab9078563412
const { 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]])
#
-
start
<integer> 新的Buffer
将开始的位置。默认值:0
。¥
start
<integer> Where the newBuffer
will start. Default:0
. -
end
<integer> 新的Buffer
将结束的位置(不包括在内)。默认值:buf.length
。¥
end
<integer> Where the newBuffer
will end (not inclusive). Default:buf.length
. -
返回:<Buffer>
¥Returns: <Buffer>
返回一个新的 Buffer
,它引用与原始内存相同的内存,但由 start
和 end
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
indexes.
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: !bc
const { 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]])
#
-
start
<integer> 新的Buffer
将开始的位置。默认值:0
。¥
start
<integer> Where the newBuffer
will start. Default:0
. -
end
<integer> 新的Buffer
将结束的位置(不包括在内)。默认值:buf.length
。¥
end
<integer> Where the newBuffer
will end (not inclusive). Default:buf.length
. -
返回:<Buffer>
¥Returns: <Buffer>
返回一个新的 Buffer
,它引用与原始内存相同的内存,但由 start
和 end
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
indexes.
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()
#
将 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()
#
将 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()
#
将 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。start
和 end
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
是 '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: té
const { 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()
#
-
返回:<Iterator>
¥Returns: <Iterator>
为 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
// 114
const { 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 tobuf
. -
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 writestring
. 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 exceedbuf.length - offset
). Default:buf.length - offset
. -
encoding
<string>string
的字符编码。默认值:'utf8'
。¥
encoding
<string> The character encoding ofstring
. 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 buf
的 offset
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: ${buffer.toString('utf8', 8, 10)}`);
// Prints: 2 bytes : ab
const { Buffer } = require('node:buffer');
const buf = Buffer.alloc(256);
const len = buf.write('\u00bd + \u00bc = \u00be', 0);
console.log(`${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 tobuf
. -
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.
将 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 tobuf
. -
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.
将 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 tobuf
. -
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.
将 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 tobuf
. -
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.
将 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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为大端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为小端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 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 tobuf
. -
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 satisfy0 <= 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.
将 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 tobuf
. -
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 satisfy0 <= 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.
将 value
写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为大端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为小端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为大端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为小端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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 satisfy0 < byteLength <= 6
. -
返回:<integer>
offset
加上写入的字节数。¥Returns: <integer>
offset
plus the number of bytes written.
将 value
的 byteLength
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 tobuf
. -
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 satisfy0 <= 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 satisfy0 < byteLength <= 6
. -
返回:<integer>
offset
加上写入的字节数。¥Returns: <integer>
offset
plus the number of bytes written.
将 value
的 byteLength
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 tobuf
. -
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 satisfy0 <= 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.
将 value
写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为大端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为小端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为大端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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.
将 value
作为小端序写入 buf
中指定的 offset
。value
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 tobuf
. -
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 satisfy0 <= 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 satisfy0 < byteLength <= 6
. -
返回:<integer>
offset
加上写入的字节数。¥Returns: <integer>
offset
plus the number of bytes written.
将 value
的 byteLength
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 tobuf
. -
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 satisfy0 <= 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 satisfy0 < byteLength <= 6
. -
返回:<integer>
offset
加上写入的字节数。¥Returns: <integer>
offset
plus the number of bytes written.
将 value
的 byteLength
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)
#
-
array
<integer[]> 要从中复制的字节数组。¥
array
<integer[]> An array of bytes to copy from.
¥See Buffer.from(array)
.
new Buffer(arrayBuffer[, byteOffset[, length]])
#
Buffer.from(arrayBuffer[, byteOffset[, length]])
。¥Stability: 0 - Deprecated: Use
Buffer.from(arrayBuffer[, byteOffset[, length]])
instead.
-
arrayBuffer
<ArrayBuffer> | <SharedArrayBuffer>ArrayBuffer
、SharedArrayBuffer
、或TypedArray
的.buffer
属性。¥
arrayBuffer
<ArrayBuffer> | <SharedArrayBuffer> AnArrayBuffer
,SharedArrayBuffer
or the.buffer
property of aTypedArray
. -
byteOffset
<integer> 要暴露的第一个字节的索引。默认值:0
。¥
byteOffset
<integer> Index of first byte to expose. Default:0
. -
length
<integer> 要暴露的字节数。默认值:arrayBuffer.byteLength - byteOffset
。¥
length
<integer> Number of bytes to expose. Default:arrayBuffer.byteLength - byteOffset
.
参见 Buffer.from(arrayBuffer[, byteOffset[, length]])
。
¥See
Buffer.from(arrayBuffer[, byteOffset[, length]])
.
new Buffer(buffer)
#
-
buffer
<Buffer> | <Uint8Array> 要从中复制数据的现有Buffer
或Uint8Array
。¥
buffer
<Buffer> | <Uint8Array> An existingBuffer
orUint8Array
from which to copy data.
¥See Buffer.from(buffer)
.
new Buffer(size)
#
Buffer.alloc()
(另请参阅 Buffer.allocUnsafe()
)。¥Stability: 0 - Deprecated: Use Buffer.alloc()
instead (also see
Buffer.allocUnsafe()
).
参见 Buffer.alloc()
和 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])
#
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 ofstring
. Default:'utf8'
.
参见 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])
#
-
sources
<string[]> | <ArrayBuffer[]> | <TypedArray[]> | <DataView[]> | <Blob[]> | <File[]> 将存储在File
中的字符串数组、<ArrayBuffer>、<TypedArray>、<DataView>、<File> 或 <Blob> 对象,或此类对象的任意组合。¥
sources
<string[]> | <ArrayBuffer[]> | <TypedArray[]> | <DataView[]> | <Blob[]> | <File[]> An array of string, <ArrayBuffer>, <TypedArray>, <DataView>, <File>, or <Blob> objects, or any mix of such objects, that will be stored within theFile
. -
fileName
<string> 文件名。¥
fileName
<string> The name of the file. -
options
<Object>-
endings
<string>'transparent'
或'native'
之一。设置为'native'
时,字符串源部分中的行结束将转换为require('node:os').EOL
指定的平台原生行结束。¥
endings
<string> One of either'transparent'
or'native'
. When set to'native'
, line endings in string source parts will be converted to the platform native line-ending as specified byrequire('node:os').EOL
. -
type
<string> 文件内容类型。¥
type
<string> The File content-type. -
lastModified
<number> 文件的最后修改日期。默认值:Date.now()
。¥
lastModified
<number> The last modified date of the file. Default:Date.now()
.
-
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)
#
Buffer.from(data, 'base64')
。¥Stability: 3 - Legacy. Use Buffer.from(data, 'base64')
instead.
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')
和 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)
#
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')
和 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)
#
-
输入 <Buffer> | <ArrayBuffer> | <TypedArray> 要验证的输入。
¥input <Buffer> | <ArrayBuffer> | <TypedArray> The input to validate.
-
返回:<boolean>
¥Returns: <boolean>
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)
#
-
输入 <Buffer> | <ArrayBuffer> | <TypedArray> 要验证的输入。
¥input <Buffer> | <ArrayBuffer> | <TypedArray> The input to validate.
-
返回:<boolean>
¥Returns: <boolean>
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
#
buffer.constants.MAX_LENGTH
的别名。
¥An alias for buffer.constants.MAX_LENGTH
.
buffer.kStringMaxLength
#
buffer.constants.MAX_STRING_LENGTH
的别名。
¥An alias for buffer.constants.MAX_STRING_LENGTH
.
buffer.resolveObjectURL(id)
#
¥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 toURL.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)
#
-
source
<Buffer> | <Uint8Array>Buffer
或Uint8Array
实例。¥
source
<Buffer> | <Uint8Array> ABuffer
orUint8Array
instance. -
fromEnc
<string> 当前编码。¥
fromEnc
<string> The current encoding. -
toEnc
<string> 目标编码。¥
toEnc
<string> To target encoding. -
返回:<Buffer>
¥Returns: <Buffer>
将给定的 Buffer
或 Uint8Array
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 fromEnc
或 toEnc
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'
和 '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
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)
#
Buffer.allocUnsafeSlow()
。¥Stability: 0 - Deprecated: Use Buffer.allocUnsafeSlow()
instead.
¥See Buffer.allocUnsafeSlow()
.
缓冲区常量#
¥Buffer constants
buffer.constants.MAX_LENGTH
#
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,此值当前为 253 - 1(约 8 PiB)。
¥On 64-bit architectures, this value currently is 253 - 1 (about 8 PiB).
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
#
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()
和 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)
和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 newBuffer
object of the specified size. Prior to Node.js 8.0.0, the memory allocated for suchBuffer
instances is not initialized and can contain sensitive data. SuchBuffer
instances must be subsequently initialized by using eitherbuf.fill(0)
or by writing to the entireBuffer
before reading data from theBuffer
. While this behavior is intentional to improve performance, development experience has demonstrated that a more explicit distinction is required between creating a fast-but-uninitializedBuffer
versus creating a slower-but-saferBuffer
. Since Node.js 8.0.0,Buffer(num)
andnew Buffer(num)
return aBuffer
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 theBuffer
. -
传入
ArrayBuffer
或SharedArrayBuffer
返回Buffer
,它与给定的数组缓冲区共享分配的内存。¥Passing an
ArrayBuffer
or aSharedArrayBuffer
returns aBuffer
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()
和 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.
-
Buffer.from(array)
返回一个新的Buffer
,其中包含提供的八位字节的副本。¥
Buffer.from(array)
returns a newBuffer
that contains a copy of the provided octets. -
Buffer.from(arrayBuffer[, byteOffset[, length]])
返回一个新的Buffer
,它与给定的ArrayBuffer
共享相同的分配内存。¥
Buffer.from(arrayBuffer[, byteOffset[, length]])
returns a newBuffer
that shares the same allocated memory as the givenArrayBuffer
. -
Buffer.from(buffer)
返回一个新的Buffer
,其中包含给定Buffer
的内容的副本。¥
Buffer.from(buffer)
returns a newBuffer
that contains a copy of the contents of the givenBuffer
. -
Buffer.from(string[, encoding])
返回一个新的Buffer
,其中包含所提供字符串的副本。¥
Buffer.from(string[, encoding])
returns a newBuffer
that contains a copy of the provided string. -
Buffer.alloc(size[, fill[, encoding]])
返回指定大小的新初始化Buffer
。此方法比Buffer.allocUnsafe(size)
慢,但保证新创建的Buffer
实例永远不会包含可能敏感的旧数据。如果size
不是数值,则会抛出TypeError
。¥
Buffer.alloc(size[, fill[, encoding]])
returns a new initializedBuffer
of the specified size. This method is slower thanBuffer.allocUnsafe(size)
but guarantees that newly createdBuffer
instances never contain old data that is potentially sensitive. ATypeError
will be thrown ifsize
is not a number. -
Buffer.allocUnsafe(size)
和Buffer.allocUnsafeSlow(size)
分别返回指定size
的新的未初始化的Buffer
。由于Buffer
未初始化,分配的内存段可能包含可能敏感的旧数据。¥
Buffer.allocUnsafe(size)
andBuffer.allocUnsafeSlow(size)
each return a new uninitializedBuffer
of the specifiedsize
. Because theBuffer
is uninitialized, the allocated segment of memory might contain old data that is potentially sensitive.
如果 size
小于或等于 Buffer.poolSize
的一半,则 Buffer.allocUnsafe()
、Buffer.from(string)
、Buffer.concat()
和 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()
, Buffer.from(string)
,
Buffer.concat()
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()
和 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()
和 Buffer.allocUnsafeSlow()
"不安全"?#
¥What makes Buffer.allocUnsafe()
and Buffer.allocUnsafeSlow()
"unsafe"?
调用 Buffer.allocUnsafe()
和 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.