To illustrate my point, here is an example of a two-route [representational state transfer](http://en.wikipedia.org/wiki/Representational_state_transfer) (REST) API server, i.e., we have only two endpoints and they are also called *routes*. In this application, we use only core Node.js modules for server functions. A single &quot;userland&quot;/external native MongoDB driver module is used for persistence. This example is taken from beginner-friendly [Full Stack JavaScript](https://github.com/azat-co/fullstack-javascript) (<http://https://github.com/azat-co/fullstack-javascript>)[Apress, 2018]:

const http = require('http')

const util = require('util')

const querystring = require('querystring')

const mongo = require('mongodb')

const host = process.env.MONGOHQ_URL ||

'mongodb://@127.0.0.1:27017'

mongo.Db.connect(host, (error, client) => {

if (error) throw error;

let collection = new mongo.Collection(

};

}

);

const port = process.env.PORT || 5000

app.listen(port)

})

Create a `server.js` file in the `hello-simple` folder:

const express = require('express')

let app = express()

app.all('*', (req, res) => {

res.send('Welcome to the Practical Node.js!')

})

app.listen(3000,

() => {console.log('Open at localhost:3000')}

)

Then launch it with `node server.js` to see "Welcome to the Practical Node.js!" in a browser at <http://localhost:3000/>. You first Express app is working!

***Figure 2-5.** The result of using Express.js Generator*

If you don&#39;t have computer in front of your right now, here&#39;s the full code of `express-styl/app.js` using Express.js Generator v4.15.0. The server file has routes from `routes` folder, stylus and a rudimentary error handler (the `;` and `var` style is preserved from the code generated by the tool)

- The `app.js` file

Another way to create a `package.json` file (without using `$ npm init`) is to type or copy and paste `package.json` and run `$ npm install`:

```js

{{

"name": "hello-advanced",

"version": "0.0.1",

"private": true,

"pug": "2.0.0-rc.4"

}

}

In the end, the `node_modules` folder should be filled with the corresponding libraries.

Here&#39;s the full source code of the `app.js` file for your reference:

```js

const express = require('express')

const http = require('http')

const path = require('path')

let app = express()

app.set('port', process.env.PORT || 3000)

app.set('views', path.join(__dirname, 'views'))

app.set('view engine', 'pug')

app.all('*', (req, res) => {

res.render(

'index',

{msg: 'Welcome to the Practical Node.js!'}

)

})

http

.createServer(app)

.listen(

app.get('port'),

() => {

console.log(`Express.js server is listening on port ${app.get('port')}`)

}

)

Before we can run this server, we need to create the `index.pug` file in the `views` folder.