A quickstart guide for Node.js & its cryptographic module

Dimitris Prasakis

Jan 14·3 min read

This article is made for experienced engineers who want to dive into the core of node.js fast and kick-start their full-stack JavaScript career. Reading the code (instead of trying to understand concepts through words) is usually the easiest way to learn a new language. Therefore, there will be little, to no text.

Requirements for this guide:

• Vanilla JavaScript (ES6)
• Object-oriented programming
• HTTP protocol
• Basic understanding of cryptography

if (beginner_programmer || want_detailed_tutorial): 
   exit()
else:
   continue

Introduction

Keypoints

• Build on C++, node.js allows developers to write server-side code with JavaScript, therefore making full-stack JS development possible.
• It is fast. Node.js is single-threaded but handles requests/responses in parallel (compared to e.g serial handling of php).

Node Version Manager (nvm)

Choose nvm instead of apt to install node on your Linux machine.

user@ubuntu:~$ sudo apt get nodejs ❌
user@ubuntu:~$ nvm install node ✅
Downloading and installing node latest version 
blah blah...user@ubuntu:~$ node -v
v15.5.1

Node Package Manager (npm)

npm is for node, what apt is for unix, composer for php, pip for python.

user@ubuntu:~$ npm install some_module

Your first program

user@ubuntu:~$ echo "
console.log('Hello medium!')" > hello.js
user@ubuntu:~$ node hello.js 
Hello medium!

Modules

The node.js libraries are called modules. Modules can be installed with npm and be required in .js files.

user@ubuntu:~$ npm install some_module 

Other .js files can be required by a script too, as long as they are exported first.

Building a simple server in Node.js

Install the module called express with npm.

req stands for (HTTP) request, res stands for (HTTP) response. Express module is great for handling incoming and outgoing server traffic.

Fetching GET URL parameters

Lets hit: http://127.0.0.1:3000/?var=value1&var2=value2

OS Environmental Variables

With Node.js, JS can access operating systems environmental variables

user@ubuntu:~$ node
> console.log(process.platform)
linux
> console.log(process.env.SHELL)
/bin/bash
> console.log(process.env.PWD)
/home/user

File system

With Node.js, JS can operate on files:

Events

Much of the Node.js core API is built around an idiomatic asynchronous event-driven architecture in which certain kinds of objects (called “emitters”) emit named events that cause Function objects ("listeners") to be called. — Official docs

The function .on() specifies the callback when the connection event occurs:

Handling errors is always wise

DNS Resolver

Node can handle DNS requests too.

or even host a full DNS server

Crypto Module

Node.js offers a wide variety of native cryptographic implementations. No need for external libraries anymore.

Diffie-hellman key exchange (made easy)

Now, it's the right moment for an introduction to Tom Waits.

What about singing… ehm signing a signature?

and verifying it!

Now, that is enough information. These examples should have given you a good understanding of the basics of how Node.js operates.

Once you master the basics, consider reading about the way that node handles the MVC framework. A google search about “routing and controllers of Express module” should be enough to give you an idea of how to structure a node.js project, whether this is an API, a microservice, or a part of a full-stack app with a language such as React.js on the front.