Introduction to Node.js

const { function createServer<Request extends typeof IncomingMessage = typeof IncomingMessage, Response extends typeof ServerResponse = typeof ServerResponse>(requestListener?: RequestListener<Request, Response>): Server<Request, Response> (+1 overload)
Returns a new instance of 
{@link 
Server
}
.

The `requestListener` is a function which is automatically
added to the `'request'` event.

```js
import http from 'node:http';

// Create a local server to receive data from
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    data: 'Hello World!',
  }));
});

server.listen(8000);
```

```js
import http from 'node:http';

// Create a local server to receive data from
const server = http.createServer();

// Listen to the request event
server.on('request', (request, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    data: 'Hello World!',
  }));
});

server.listen(8000);
```
@sincev0.1.13createServer } = 
var require: NodeJS.Require
(id: string) => any
Used to import modules, `JSON`, and local files.
@sincev0.1.13require('node:http');

const const hostname: "127.0.0.1"hostname = '127.0.0.1';
const const port: 3000port = 3000;

const const server: Server<typeof IncomingMessage, typeof ServerResponse>server = createServer<typeof IncomingMessage, typeof ServerResponse>(requestListener?: RequestListener<typeof IncomingMessage, typeof ServerResponse> | undefined): Server<...> (+1 overload)
Returns a new instance of 
{@link 
Server
}
.

The `requestListener` is a function which is automatically
added to the `'request'` event.

```js
import http from 'node:http';

// Create a local server to receive data from
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    data: 'Hello World!',
  }));
});

server.listen(8000);
```

```js
import http from 'node:http';

// Create a local server to receive data from
const server = http.createServer();

// Listen to the request event
server.on('request', (request, res) => {
  res.writeHead(200, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify({
    data: 'Hello World!',
  }));
});

server.listen(8000);
```
@sincev0.1.13createServer((req: IncomingMessagereq, 
res: ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
}res) => {
  
res: ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
}res.ServerResponse<Request extends IncomingMessage = IncomingMessage>.statusCode: number
When using implicit headers (not calling `response.writeHead()` explicitly),
this property controls the status code that will be sent to the client when
the headers get flushed.

```js
response.statusCode = 404;
```

After response header was sent to the client, this property indicates the
status code which was sent out.
@sincev0.4.0statusCode = 200;
  
res: ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
}res.
OutgoingMessage<IncomingMessage>.setHeader(name: string, value: number | string | readonly string[]): ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
}
Sets a single header value. If the header already exists in the to-be-sent
headers, its value will be replaced. Use an array of strings to send multiple
headers with the same name.
@sincev0.4.0@paramname Header name@paramvalue Header valuesetHeader('Content-Type', 'text/plain');
  
res: ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
}res.
Stream.Writable.end(chunk: any, cb?: () => void): ServerResponse<IncomingMessage> & {
    req: IncomingMessage;
} (+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!
```
@sincev0.9.4@paramchunk Optional data to write. For streams not operating in object mode, `chunk` must be a {string}, {Buffer},
{TypedArray} or {DataView}. For object mode streams, `chunk` may be any JavaScript value other than `null`.@paramencoding The encoding if `chunk` is a string@paramcallback Callback for when the stream is finished.end('Hello World');
});

const server: Server<typeof IncomingMessage, typeof ServerResponse>server.Server.listen(port?: number, hostname?: string, listeningListener?: () => void): Server<typeof IncomingMessage, typeof ServerResponse> (+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(const port: 3000port, const hostname: "127.0.0.1"hostname, () => {
  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-v22.x/api/process.html#processstdout) and
[`process.stderr`](https://nodejs.org/docs/latest-v22.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-v22.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/v22.x/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-v22.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-v22.x/api/util.html#utilformatformat-args) for more information.
@sincev0.1.100log(`Server running at http://${const hostname: "127.0.0.1"hostname}:${const port: 3000port}/`);
});