For those who want to jump into learning Node.js with a minimum of noise, here is one way to approach it:

Note: This is easy on a Linux machine. (I used Ubuntu v. 16.04 LTS.)

First Install NVM

Note: you may need to install curl if it is not already installed. If you do, in a terminal window, type

sudo apt-get install curl

Then

curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.5/install.sh | bash

Restart terminal, then check version with this:

nvm --version

Install Node

nvm install 6.11.4

(When installing a Node.js instance, nvm will also install a compatible npm version.)

Other commands: (from: https://www.sitepoint.com/quick-tip-multiple-versions-node-nvm/)

To check which npm version:

npm -v

To check which node versions are available

nvm ls-remote

Install the latest Node.js version

nvm install node

Uninstall any instance

nvm uninstall 4.8.4

Switch to node ver 4.8.4

nvm use 4.8.4

Switch to latest Node.js version

nvm use node

Check which versions you have installed

nvm ls

Create a custom alias

nvm alias awesome-version 4.8.4

use the alias version

nvm use awesome-version

Delete an alias

nvm unalias awesome-version

Simple node

Start node

node

Send text to the console

console.log('Aggie & Dave');

Exit node

process.exit()

or

.exit

or

Ctrl+C [enter] 

Express

Open terminal

  mkdir myApp
  cd myApp
  npm init  (entry point: app.js)
  npm install express --save   (creates all necessary files)

Very simple app

Create a file called app.js

var express = require('express');
var app = express();
app.get("/", function(req, res) {
 res.send("<h1>Home Page</h1>");
});
var server = app.listen(3000, function(){
console.log("Listening on port 3000");
});

In the terminal window, enter the following command to run the Node app (which launches the server):

node app.js

Open a browser. Navigate to: http://localhost:3000

App with multiple routes

var express = require('express');
var app = express();
app.get('/', function(req, res) {
  res.send('<h1>Home</h1>');
});
app.get('/aggie', function(req, res) {
  res.send('<h1>Aggie the dog!</h1>');
});
app.get('/julie', function(req, res) {
  res.send('<h1>Julie is great.</h1>');
});
var server = app.listen(3000, function() {
  console.log('Listening on port 3000');
});

Open a browser. Navigate to: http://localhost:3000