Simple TCP Client and Server in Node.js (Covering all useful Properties & Methods)

net-client.js

const net = require("net");

// creating a custom socket client and connecting it....
const client = new net.Socket();

client.connect({
	port: 2222
});

client.on("connect", ()  => {
	console.log("Client: connection established with server");

	const address = client.address();
	const port = address.port;
	const family = address.family;
	const ipaddr = address.address;
	console.log("Client is listening at port" + port);
	console.log("Client ip :" + ipaddr);
	console.log("Client is IP4/IP6 : " + family);


	// writing data to server
	client.write("Hello from client");

});

client.setEncoding("utf8");

client.on("data", function (data) {
	console.log("Data from server:" + data);
});

net-server.js

const net = require("net");

// Create the TCP server
const server = net.createServer();

// Emitted when the server closes,
// but not emitted until all connections closes.
server.on("close", () => {
	console.log("Server closed");
});

// Emitted when new client connects
server.on("connection", (socket) => {
	// this property shows the number of characters
	// currently buffered to be written.
	// Users who experience large or growing bufferSize
	// should attempt to "throttle" the data flows
	// in their program with pause() and resume().

	// bufferSize deprecated, use writableLength
	console.log(`Buffer size: ${socket.writableLength}`);

	console.log(`Remote socket ip: ${socket.remoteAddress}`);

	server.getConnections((error, connections) => {
		console.log(`Currently ${connections} connections`);
	});

	socket.setEncoding("utf-8");

	socket.setTimeout(800000, () => {
		console.log("Socket timed out");
	});


	socket.on("data", (data) => {
		const bread = socket.bytesRead;
		const bwrite = socket.bytesWritten;
		console.log("Bytes read : " + bread);
		console.log("Bytes written : " + bwrite);
		console.log("Data sent to server : " + data);

		//echo data
		const is_kernel_buffer_full = socket.write("Data ::" + data);
		if (is_kernel_buffer_full) {
			console.log("Data was flushed successfully from kernel buffer i.e written successfully!");
		} else {
			socket.pause();
		}
	});

	socket.on("drain", () => {
		console.log("write buffer is empty now .. u can resume the writable stream");
		socket.resume();
	});

	socket.on("error", (error) => {
		console.log("Error : " + error);
	});

	socket.on("timeout", () => {
		console.log("Socket timed out !");
		socket.end("Timed out!");
		// can call socket.destroy() here too.
	});

	socket.on("end", (data) => {
		console.log("Socket ended from other end!");
		console.log("End data : " + data);
	});

	socket.on("close", (error) => {
		const bread = socket.bytesRead;
		const bwrite = socket.bytesWritten;
		console.log("Bytes read : " + bread);
		console.log("Bytes written : " + bwrite);
		console.log("Socket closed!");
		if (error) {
			console.log("Socket was closed coz of transmission error");
		}
	});

	setTimeout(() => {
		const isdestroyed = socket.destroyed;
		console.log("Socket destroyed:" + isdestroyed);
		socket.destroy();
	}, 1200000);

});

// Emits when any error occurs
server.on("error", (error) => {
	console.log(`Error: ${error.name}`);
	console.log(error.message);
});

server.on("listening", () => {
	const address = server.address();
	typeof address === "string"
		? console.log(`TCP server listening at ${address}`)
		: console.log(`TCP server listening at ${address.address}`);
});

server.listen({
	port: 1227,
	host: "0.0.0.0",
	backlog: 300
});