net

The net module provides Node.js-compatible TCP networking APIs for JSH applications.

createServer()

Creates a TCP server.

Supported signatures:

• createServer([connectionListener])

• createServer([options][, connectionListener])

• Returns: Server

• If connectionListener is provided, it is registered for the connection event.

Syntax

createServer([options][, connectionListener])

Usage example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

const net = require('net');

const server = net.createServer((socket) => {
	socket.on('data', (data) => {
		const msg = data.toString();
		socket.write('Echo: ' + msg);
	});
});

server.listen(0, '127.0.0.1');

createConnection() / connect()

Creates a TCP client socket and connects to a server.

Supported signatures:

• createConnection(port[, host][, connectListener])

• createConnection(options[, connectListener])

• connect(...) (alias of createConnection)

• Returns: Socket

Syntax

createConnection(port[, host][, connectListener])
createConnection(options[, connectListener])
connect(port[, host][, connectListener])
connect(options[, connectListener])

Usage example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

const net = require('net');

const client = net.createConnection({ port: 5650, host: '127.0.0.1' }, () => {
	client.write('Hello Server\n');
});

client.on('data', (data) => {
	console.println(data.toString().trim());
	client.end();
});

IP validation utilities

Utility functions to validate IP string values.

• isIP(input) returns 4, 6, or 0
• isIPv4(input) returns boolean
• isIPv6(input) returns boolean

Usage example

1
2
3
4

const net = require('net');
console.println(net.isIP('127.0.0.1')); // 4
console.println(net.isIPv4('127.0.0.1')); // true
console.println(net.isIPv6('::1')); // true

Server

TCP server object returned by createServer().

Main properties

• listening
• connections

Server methods

• listen(port[, host][, backlog][, callback])
• listen(options[, callback])
• close([callback])
• address()
• getConnections([callback])
• ref()
• unref()

Server events

• connection (Socket)
• listening ()
• close ()
• error (Error)

Usage example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11

const net = require('net');
const server = net.createServer();

server.on('listening', () => {
	const addr = server.address();
	console.println(addr.family, addr.address, addr.port);
});

server.listen(0, '127.0.0.1', () => {
	console.println('server ready');
});

Socket

TCP client/server connection object.

Main properties

• connecting
• readable
• writable
• destroyed
• bytesRead
• bytesWritten
• localAddress
• localPort
• remoteAddress
• remotePort
• remoteFamily

Socket methods

• connect(port[, host][, connectListener])
• connect(options[, connectListener])
• write(data[, encoding][, callback])
• end([data[, encoding]][, callback])
• destroy([error])
• setTimeout(timeout[, callback])
• setNoDelay([noDelay])
• setKeepAlive([enable][, initialDelay])
• setEncoding([encoding])
• address()
• pause()
• resume()
• ref()
• unref()

Socket events

• connect ()
• data (Buffer)
• end ()
• close (hadError)
• error (Error)
• finish ()

Behavior notes

• data event payload is emitted as Buffer.
• write() supports string, Buffer, Array, and Uint8Array-compatible values.
• pause() / resume() are currently no-op in the native implementation.

Usage example

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16

const net = require('net');
const client = net.connect(5650, '127.0.0.1');

client.on('connect', () => {
	client.setNoDelay(true);
	client.write('ping\n');
});

client.on('data', (data) => {
	console.println('received:', data.toString().trim());
	client.end();
});

client.on('close', (hadError) => {
	console.println('closed, hadError=', hadError);
});