TCP 是一种面向连接的传输层协议，为应用层提供可靠的数据传输服务。它是因特网协议栈（TCP/IP 协议族） 的核心协议之一，广泛应用于需要数据完整性和顺序性保障的场景，如网页浏览（HTTP/HTTPS）、电子邮件（SMTP/IMAP）等

# 特点

• 面向连接
  • 在通信前，必须通过三次握手建立连接。
  • 在数据传输完成后，通过四次挥手释放连接。
• 可靠传输
  • 数据分段：将数据分成适合传输的小段。
  • 序列号：每个数据段都有序列号，保证数据按顺序组装。
  • 确认机制：接收方通过 ACK（Acknowledgment）确认接收到的数据。
  • 重传机制：若超时未收到确认，自动重发丢失的数据。
• 流量控制
  • 使用滑动窗口机制，调节发送方的速度，防止接收方因负载过高而丢包。
• 拥塞控制
  • 根据网络状况动态调整发送速度，避免因网络过载而导致通信质量下降。

• 全双工通信
  • 数据可以同时在两端传输，发送方和接收方均可独立发送和接收数据。

# 报文格式

TCP 数据报文由头部和数据部分组成。TCP 头部长度通常为 20 字节（不含可选字段），主要包含以下字段：

ts
// TCP.ts，模拟 TCP 头部

enum TCPFlags {
  SYN, // 同步请求建立连接，用于 三次握手的第一步。
  ACK, // 确认已接收到的数据，用于响应对方的报文。
  FIN, // 结束请求断开连接，用于 四次挥手的第一步。
  RST, // 重置连接，用于异常终止连接或拒绝连接请求。
  PSH, // 立即推送数据到接收方应用层，而不必等待缓冲区填满。
  URG, // 紧急数据，需要接收方优先处理（紧急数据结束位置由紧急指针 Urgent Pointer 标识）。
  ECE, // 拥塞控制，用于控制数据传输速度和流量。
  CWR, // 拥塞窗口缩小，用于避免拥塞时的数据丢失。
  NS, // 不分流，用于避免拥塞时的数据丢失。
}

interface TCPHeader {
  sourcePort: number
  destinationPort: number
  sequenceNumber: number
  acknowledgementNumber: number
  dataOffset: number
  reserved: number
  flags: number
  windowSize: number
  checksum: number
  urgentPointer: number
  options?: number[]
}

const tcpHeader: TCPHeader = {
  sourcePort: 433,
  destinationPort: 80,
  sequenceNumber: 0, // 指示本报文段数据的序号，确保数据按序组装。
  acknowledgementNumber: 0, // 确认接收到的数据序号，表示接收方期望的下一个序号。
  dataOffset: 5, // 指示 TCP 头部的长度（以 4 字节为单位），用于定位数据部分的起始位置。
  reserved: 0, // 保留未用，置 0。
  flags: TCPFlags.SYN, // 用于控制连接状态的标志位，包括 SYN、ACK、FIN 等。
  windowSize: 0, // 表示接收方当前的缓冲区大小，用于流量控制。
  checksum: 0, // 计算 TCP 头部的校验和，用于检测数据的完整性。
  urgentPointer: 0, // 表示紧急数据的位置，用于处理拥塞情况。
  options: [], // 可选字段，用于扩展 TCP 头部，包括 TCP 拥塞控制、流量控制等。
}

# 工作流程

三次握手确保了连接双方都能互相确认彼此的存在并准备好通信，而四次挥手用于保证双方都能完全关闭连接。

三次握手（建立连接）：

1. 第一次握手：
   • 客户端发送一个 SYN（同步序号）报文，表示希望建立连接。
   • SYN 报文包含客户端的初始序列号。
2. 第二次握手：
   • 服务端接收 SYN 后，发送一个带有 SYN 和 ACK 的报文，表示接受请求并同步序号。
   • ACK 用于确认接收到客户端的 SYN，SYN 用于向客户端同步序号。
3. 第三次握手：
   • 客户端接收服务端的 SYN+ACK 后，发送一个 ACK 报文，确认连接建立。

go
客户端               服务端
  SYN  ------------>
       <------------  SYN+ACK
  ACK  ------------>

四次挥手（释放连接）：

1. 第一次挥手：
   • 客户端发送一个 FIN 报文，表示不再发送数据，但可以接收数据。
2. 第二次挥手：
   • 服务端接收 FIN 后，返回一个 ACK 报文，确认关闭请求。
3. 第三次挥手：
   • 服务端发送一个 FIN 报文，表示数据传输结束，准备关闭连接。
4. 第四次挥手：
   • 客户端接收 FIN 后，返回 ACK 并进入 TIME_WAIT 状态，等待一段时间以确保服务端收到 ACK 后关闭连接。

go
客户端               服务端
  FIN  ------------>
       <------------  ACK
       <------------  FIN
  ACK  ------------>

# 数据可靠性机制

• 序列号和确认号
  • 序列号：确保数据按序传输，避免乱序。
  • 确认号：接收方发送确认号，告知发送方已成功接收的数据。
• 超时重传
  • 发送方在指定时间内未收到 ACK，会重新发送数据。
• 滑动窗口
  • 控制发送数据的大小，防止接收方的缓冲区溢出。
• 校验和
  • 用于检测数据在传输过程中是否被篡改或损坏。

# 使用Nodejs简单实现一个TCP服务端和客户端

服务端：

ts
import { function createServer(connectionListener?: (socket: Socket) => void): Server (+1 overload)
Creates a new TCP or `IPC` server.

If `allowHalfOpen` is set to `true`, when the other end of the socket
signals the end of transmission, the server will only send back the end of
transmission when `socket.end()` is explicitly called. For example, in the
context of TCP, when a FIN packed is received, a FIN packed is sent
back only when `socket.end()` is explicitly called. Until then the
connection is half-closed (non-readable but still writable). See `'end'` event and [RFC 1122](https://tools.ietf.org/html/rfc1122) (section 4.2.2.13) for more information.

If `pauseOnConnect` is set to `true`, then the socket associated with each
incoming connection will be paused, and no data will be read from its handle.
This allows connections to be passed between processes without any data being
read by the original process. To begin reading data from a paused socket, call `socket.resume()`.

The server can be a TCP server or an `IPC` server, depending on what it `listen()` to.

Here is an example of a TCP echo server which listens for connections
on port 8124:

```js
import net from 'node:net';
const server = net.createServer((c) => {
  // 'connection' listener.
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
  c.write('hello\r\n');
  c.pipe(c);
});
server.on('error', (err) => {
  throw err;
});
server.listen(8124, () => {
  console.log('server bound');
});
```

Test this by using `telnet`:

```bash
telnet localhost 8124
```

To listen on the socket `/tmp/echo.sock`:

```js
server.listen('/tmp/echo.sock', () => {
  console.log('server bound');
});
```

Use `nc` to connect to a Unix domain socket server:

```bash
nc -U /tmp/echo.sock
```
@sincev0.5.0@paramconnectionListener Automatically set as a listener for the {@link 'connection'} event.createServer } from 'node:net'

const const server: Serverserver = function createServer(connectionListener?: (socket: Socket) => void): Server (+1 overload)
Creates a new TCP or `IPC` server.

If `allowHalfOpen` is set to `true`, when the other end of the socket
signals the end of transmission, the server will only send back the end of
transmission when `socket.end()` is explicitly called. For example, in the
context of TCP, when a FIN packed is received, a FIN packed is sent
back only when `socket.end()` is explicitly called. Until then the
connection is half-closed (non-readable but still writable). See `'end'` event and [RFC 1122](https://tools.ietf.org/html/rfc1122) (section 4.2.2.13) for more information.

If `pauseOnConnect` is set to `true`, then the socket associated with each
incoming connection will be paused, and no data will be read from its handle.
This allows connections to be passed between processes without any data being
read by the original process. To begin reading data from a paused socket, call `socket.resume()`.

The server can be a TCP server or an `IPC` server, depending on what it `listen()` to.

Here is an example of a TCP echo server which listens for connections
on port 8124:

```js
import net from 'node:net';
const server = net.createServer((c) => {
  // 'connection' listener.
  console.log('client connected');
  c.on('end', () => {
    console.log('client disconnected');
  });
  c.write('hello\r\n');
  c.pipe(c);
});
server.on('error', (err) => {
  throw err;
});
server.listen(8124, () => {
  console.log('server bound');
});
```

Test this by using `telnet`:

```bash
telnet localhost 8124
```

To listen on the socket `/tmp/echo.sock`:

```js
server.listen('/tmp/echo.sock', () => {
  console.log('server bound');
});
```

Use `nc` to connect to a Unix domain socket server:

```bash
nc -U /tmp/echo.sock
```
@sincev0.5.0@paramconnectionListener Automatically set as a listener for the {@link 'connection'} event.createServer((socket: Socketsocket) => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[服务端] 连接成功')

  socket: Socketsocket.Socket.on(event: "data", listener: (data: Buffer) => void): Socket (+12 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```on('data', (data: Buffer<ArrayBufferLike>data) => {
    var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[服务端] 接收到数据:', data: Buffer<ArrayBufferLike>data)

    // 向客户端发送数据
    socket: Socketsocket.Socket.write(buffer: Uint8Array | string, cb?: (err?: Error) => void): boolean (+1 overload)
Sends data on the socket. The second parameter specifies the encoding in the
case of a string. It defaults to UTF8 encoding.

Returns `true` if the entire data was flushed successfully to the kernel
buffer. Returns `false` if all or part of the data was queued in user memory.`'drain'` will be emitted when the buffer is again free.

The optional `callback` parameter will be executed when the data is finally
written out, which may not be immediately.

See `Writable` stream `write()` method for more
information.
@sincev0.1.90@paramencoding Only used when data is `string`.write('Hello, Client.')

    // 结束连接
    // socket.end('Bye')
  })

  socket: Socketsocket.Socket.on(event: "end", listener: () => void): Socket (+12 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```on('end', () => {
    var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[服务端] 连接关闭')
  })
})

const server: Serverserver.Server.on(event: "close", listener: () => void): Server (+5 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```
@sincev0.1.101@parameventName The name of the event.@paramlistener The callback functionon('close', () => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[服务端] 停止监听')
})

const server: Serverserver.Server.listen(port?: number, listeningListener?: () => void): Server (+8 overloads)
Start a server listening for connections. A `net.Server` can be a TCP or
an `IPC` server depending on what it listens to.

Possible signatures:

* `server.listen(handle[, backlog][, callback])`
* `server.listen(options[, callback])`
* `server.listen(path[, backlog][, callback])` for `IPC` servers
* `server.listen([port[, host[, backlog]]][, callback])` for TCP servers

This function is asynchronous. When the server starts listening, the `'listening'` event will be emitted. The last parameter `callback`will be added as a listener for the `'listening'`
event.

All `listen()` methods can take a `backlog` parameter to specify the maximum
length of the queue of pending connections. The actual length will be determined
by the OS through sysctl settings such as `tcp_max_syn_backlog` and `somaxconn` on Linux. The default value of this parameter is 511 (not 512).

All 
{@link 
Socket
}
 are set to `SO_REUSEADDR` (see [`socket(7)`](https://man7.org/linux/man-pages/man7/socket.7.html) for
details).

The `server.listen()` method can be called again if and only if there was an
error during the first `server.listen()` call or `server.close()` has been
called. Otherwise, an `ERR_SERVER_ALREADY_LISTEN` error will be thrown.

One of the most common errors raised when listening is `EADDRINUSE`.
This happens when another server is already listening on the requested`port`/`path`/`handle`. One way to handle this would be to retry
after a certain amount of time:

```js
server.on('error', (e) => {
  if (e.code === 'EADDRINUSE') {
    console.error('Address in use, retrying...');
    setTimeout(() => {
      server.close();
      server.listen(PORT, HOST);
    }, 1000);
  }
});
```listen(3000, () => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[服务端] 启动成功，正在监听 3000 端口')
})

客户端：

ts
import { function createConnection(options: NetConnectOpts, connectionListener?: () => void): Socket (+2 overloads)
A factory function, which creates a new 
{@link 
Socket
}
,
immediately initiates connection with `socket.connect()`,
then returns the `net.Socket` that starts the connection.

When the connection is established, a `'connect'` event will be emitted
on the returned socket. The last parameter `connectListener`, if supplied,
will be added as a listener for the `'connect'` event **once**.

Possible signatures:

* 
{@link 
createConnection
}

* 
{@link 
createConnection
}
 for `IPC` connections.
* 
{@link 
createConnection
}
 for TCP connections.

The 
{@link 
connect
}
 function is an alias to this function.createConnection } from 'node:net'

const const socket: Socketsocket = function createConnection(options: NetConnectOpts, connectionListener?: () => void): Socket (+2 overloads)
A factory function, which creates a new 
{@link 
Socket
}
,
immediately initiates connection with `socket.connect()`,
then returns the `net.Socket` that starts the connection.

When the connection is established, a `'connect'` event will be emitted
on the returned socket. The last parameter `connectListener`, if supplied,
will be added as a listener for the `'connect'` event **once**.

Possible signatures:

* 
{@link 
createConnection
}

* 
{@link 
createConnection
}
 for `IPC` connections.
* 
{@link 
createConnection
}
 for TCP connections.

The 
{@link 
connect
}
 function is an alias to this function.createConnection({
  TcpSocketConnectOpts.host?: string | undefinedhost: '127.0.0.1',
  TcpSocketConnectOpts.port: numberport: 3000
}, () => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[客户端] 连接成功')

  // 向服务端发送数据
  const socket: Socketsocket.Socket.write(buffer: Uint8Array | string, cb?: (err?: Error) => void): boolean (+1 overload)
Sends data on the socket. The second parameter specifies the encoding in the
case of a string. It defaults to UTF8 encoding.

Returns `true` if the entire data was flushed successfully to the kernel
buffer. Returns `false` if all or part of the data was queued in user memory.`'drain'` will be emitted when the buffer is again free.

The optional `callback` parameter will be executed when the data is finally
written out, which may not be immediately.

See `Writable` stream `write()` method for more
information.
@sincev0.1.90@paramencoding Only used when data is `string`.write('Hello, Server.', () => {
    var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[客户端] 发送数据成功')
  })
})

// 当接收到服务端的数据
const socket: Socketsocket.Socket.on(event: "data", listener: (data: Buffer) => void): Socket (+12 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```on('data', (data: Buffer<ArrayBufferLike>data) => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log(`[客户端] 接收的数据${data: Buffer<ArrayBufferLike>data}`)

  function setTimeout<[]>(callback: () => void, delay?: number): NodeJS.Timeout (+2 overloads)
Schedules execution of a one-time `callback` after `delay` milliseconds.

The `callback` will likely not be invoked in precisely `delay` milliseconds.
Node.js makes no guarantees about the exact timing of when callbacks will fire,
nor of their ordering. The callback will be called as close as possible to the
time specified.

When `delay` is larger than `2147483647` or less than `1`, the `delay` will be set to `1`. Non-integer delays are truncated to an integer.

If `callback` is not a function, a `TypeError` will be thrown.

This method has a custom variant for promises that is available using `timersPromises.setTimeout()`.
@sincev0.0.1@paramcallback The function to call when the timer elapses.@paramdelay The number of milliseconds to wait before calling the `callback`.@paramargs Optional arguments to pass when the `callback` is called.@returnfor use with {@link clearTimeout}setTimeout(() => {
    // 结束连接
    const socket: Socketsocket.Socket.end(buffer: Uint8Array | string, callback?: () => void): Socket (+2 overloads)
Calling the `writable.end()` method signals that no more data will be written
to the `Writable`. The optional `chunk` and `encoding` arguments allow one
final additional chunk of data to be written immediately before closing the
stream.

Calling the 
{@link 
write
}
 method after calling 
{@link 
end
}
 will raise an error.

```js
// Write 'hello, ' and then end with 'world!'.
import fs from 'node:fs';
const file = fs.createWriteStream('example.txt');
file.write('hello, ');
file.end('world!');
// Writing more now is not allowed!
```end('Bye')
  }, 3000)
})

// 当服务端的连接关闭
const socket: Socketsocket.Socket.on(event: "end", listener: () => void): Socket (+12 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```on('end', () => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[客户端] 连接关闭')

  // 销毁连接
  const socket: Socketsocket.Stream.Readable.destroy(error?: Error): Socket
Destroy the stream. Optionally emit an `'error'` event, and emit a `'close'` event (unless `emitClose` is set to `false`). After this call, the readable
stream will release any internal resources and subsequent calls to `push()` will be ignored.

Once `destroy()` has been called any further calls will be a no-op and no
further errors except from `_destroy()` may be emitted as `'error'`.

Implementors should not override this method, but instead implement `readable._destroy()`.
@sincev8.0.0@paramerror Error which will be passed as payload in `'error'` eventdestroy()
})

// 客户端的连接关闭
const socket: Socketsocket.Socket.on(event: "close", listener: (hadError: boolean) => void): Socket (+12 overloads)
Adds the `listener` function to the end of the listeners array for the event
named `eventName`. No checks are made to see if the `listener` has already
been added. Multiple calls passing the same combination of `eventName` and
`listener` will result in the `listener` being added, and called, multiple times.

```js
server.on('connection', (stream) => {
  console.log('someone connected!');
});
```

Returns a reference to the `EventEmitter`, so that calls can be chained.

By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the
event listener to the beginning of the listeners array.

```js
import { EventEmitter } from 'node:events';
const myEE = new EventEmitter();
myEE.on('foo', () => console.log('a'));
myEE.prependListener('foo', () => console.log('b'));
myEE.emit('foo');
// Prints:
//   b
//   a
```on('close', () => {
  var console: Console
The `console` module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.

The module exports two specific components:

* A `Console` class with methods such as `console.log()`, `console.error()` and `console.warn()` that can be used to write to any Node.js stream.
* A global `console` instance configured to write to [`process.stdout`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v20.x/api/process.html#processstderr). The global `console` can be used without importing the `node:console` module.

_**Warning**_: The global console object's methods are neither consistently
synchronous like the browser APIs they resemble, nor are they consistently
asynchronous like all other Node.js streams. See the [`note on process I/O`](https://nodejs.org/docs/latest-v20.x/api/process.html#a-note-on-process-io) for
more information.

Example using the global `console`:

```js
console.log('hello world');
// Prints: hello world, to stdout
console.log('hello %s', 'world');
// Prints: hello world, to stdout
console.error(new Error('Whoops, something bad happened'));
// Prints error message and stack trace to stderr:
//   Error: Whoops, something bad happened
//     at [eval]:5:15
//     at Script.runInThisContext (node:vm:132:18)
//     at Object.runInThisContext (node:vm:309:38)
//     at node:internal/process/execution:77:19
//     at [eval]-wrapper:6:22
//     at evalScript (node:internal/process/execution:76:60)
//     at node:internal/main/eval_string:23:3

const name = 'Will Robinson';
console.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to stderr
```

Example using the `Console` class:

```js
const out = getStreamSomehow();
const err = getStreamSomehow();
const myConsole = new console.Console(out, err);

myConsole.log('hello world');
// Prints: hello world, to out
myConsole.log('hello %s', 'world');
// Prints: hello world, to out
myConsole.error(new Error('Whoops, something bad happened'));
// Prints: [Error: Whoops, something bad happened], to err

const name = 'Will Robinson';
myConsole.warn(`Danger ${name}! Danger!`);
// Prints: Danger Will Robinson! Danger!, to err
```
@see[source](https://github.com/nodejs/node/blob/v20.11.1/lib/console.js)console.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)
Prints to `stdout` with newline. Multiple arguments can be passed, with the
first used as the primary message and all additional used as substitution
values similar to [`printf(3)`](http://man7.org/linux/man-pages/man3/printf.3.html)
(the arguments are all passed to [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args)).

```js
const count = 5;
console.log('count: %d', count);
// Prints: count: 5, to stdout
console.log('count:', count);
// Prints: count: 5, to stdout
```

See [`util.format()`](https://nodejs.org/docs/latest-v20.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log('[客户端] 关闭')
})