Hello World in node.js

A simple print statement that prints “Hello World!”

console.log("Hello World!");

A node js http server that prints “Hello World!” to all requests.

// Load the http module to create an http server.
var http = require('http');

// Configure the HTTP server to print Hello World! to all requests.
var server = http.createServer(function (request, response) {
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.end("Hello World!\n");
});

// Listen on port 1234
server.listen(1234);

console.log('You will see "Hello World!"" if you open up a browser and go to the url http://localhost:1234/');

A node js tcp server that prints “Hello World!” to all requests.

// Load the net module to create a tcp server.
var net = require('net');

// Create a new TCP server.
var server = net.createServer(function (socket) {

  
  console.log("Connection from " + socket.remoteAddress);
  socket.end("Hello World!\n"); //Print Hello World! to all requests.

});

// Listen to port 9123 on localhost
server.listen(9123, "localhost");

// Put a friendly message on the terminal
console.log("You can connect go to http://localhost:9123 or issue one of these commands on your terminal");
console.log("curl http://localhost:9123");
console.log("nc localhost 9123");
console.log("netcat localhost 9123");

Assume you have node installed and you’ve created 3 js files for the above 3 programs. You can run them by these commands

node helloworld.js
node helloworld_http_server.js
node helloworld_tcp_server.js