This script just for beginner how to show hello world.

hello_on_nodejs

var express = require('express');
var app = express();

app.get('/', function (req, res) {
  res.send('Hello World!');
});

  var server = app.listen(3000, function () {
  var host   = server.address().address;
  var port   = server.address().port;

  console.log('Example app listening at http://%s:%s', host, port);
});