Free lesson · Node.js Deep Dive
Why This Course Exists, Why I'm Teaching It
Why This Course Exists, Why I'm Teaching It
I was 26 the first time I wrote JavaScript.
I had a degree in Economics from Kyiv Polytechnic. I'd spent four years working as a financial analyst at PwC's Warsaw office, building Excel models for retail clients - promotional spend analysis, inventory turnover, that kind of work. I was good at it. I was also bored out of my mind.
A friend who worked at a Polish startup kept showing me what his frontend team was doing - building things, shipping them, watching real people use them. The next Saturday I opened freeCodeCamp's introductory JavaScript course, and the same week I subscribed to The Odin Project. I gave myself a year. If I couldn't make the switch, I'd go back to spreadsheets.
That year was harder than I expected. My first eleven tech interviews were rejections. Not "you were close" rejections - "we're looking for someone with a computer science background" rejections. I remember one specifically: I'd spent six weeks preparing for a junior frontend role at a digital agency in Warsaw. They asked me about time complexity. I'd never heard the term. I tried to reason it out. The interviewer was kind about it. I cried in the bathroom afterwards.
Nobody had told me what I didn't know. That was the thing. The CS-degree engineers I was interviewing against had spent four years internalizing concepts I'd never even heard names for. Big O notation, hash tables, the call stack, the heap, how the JavaScript runtime actually worked. They didn't think about these things explicitly - they just had them, the way I had a mental model of cash flow statements.
I got a job eventually. A small digital agency hired me as a junior on a six-month trial. I shipped enough work in those six months to stay. From there I joined Zalando in Berlin as a regular SWE, got promoted to Senior, then moved to Microsoft. Today I'm a Software Engineer II on the Azure DevTools team in Redmond. I work on VS Code Remote Development - the part of VS Code that lets you SSH into a server and write code there as if it were local - and on Microsoft's GitHub Copilot integration. Every VS Code release ships with my code in it.
I'm telling you this because I want you to know two things going in.
One: I taught myself everything I'm about to teach you, starting from where you are. I am not going to skip the parts that confused me. I'm going to slow down at the places I remember getting stuck, because there's a good chance you'll get stuck there too. The course is written from memory of being on your side of the screen.
Two: I write production Node.js code today. I'm not a former engineer who became a course author. The VS Code Remote Development tooling I work on is heavily Node.js. The patterns I'm going to teach you aren't tutorial patterns - they're the patterns I actually use, that ship to millions of VS Code users every release. When I tell you "this is how you should structure your error handling," I'm telling you what we do at Microsoft because the alternatives bit us.
What This Course Is
This is a course on Node.js from scratch through production-grade depth. It assumes you know JavaScript at the syntax level - const, let, arrow functions, async/await, the basic Promise API - but doesn't assume much beyond that. We'll fix the gaps in Module 2.
The course covers everything from "what is Node.js and why does it exist" through "how do I run a Node.js service in production, debug it, profile it, and not have it page me at 3am." That's a lot of material. The full course is 25 modules. I expect most people to take 6-12 months to work through it carefully, depending on how much you commit per week.
What makes this course different from the hundred other Node.js courses you could pick:
Depth on the engine, not just the syntax. Most Node tutorials teach you app.get('/users', handler) and call it a day. They don't tell you what app.get actually does, how the event loop schedules handler, what happens when a thousand requests arrive at the same time. This course goes there. By the end of Module 3, you'll be able to draw the event loop from memory and predict the execution order of code that mixes setTimeout, setImmediate, process.nextTick, and promises. That's the depth senior engineers have. It's the depth interviews at Microsoft, Google, and Meta probe for.
Production patterns I actually use. When we get to error handling (Module 15), I'm going to show you the structure we use at Microsoft. When we get to debugging (Module 13), I'm going to show you the inspector protocol the way I actually drive it. When we get to performance engineering (Module 14), the techniques are the ones I've used to find real bottlenecks in real systems. The course is opinionated because in production, opinionated wins.
A voice that respects your time. I'm not going to pad. I'm not going to repeat the same concept three times in different words. I'm not going to use marketing language about how Node.js "empowers" you. You're an adult; I'm an adult; we both have other things to do.
What This Course Is Not
Not a JavaScript course. If you don't know JavaScript syntax, learn that first. I recommend freeCodeCamp's JavaScript Algorithms and Data Structures for the bare minimum, and The Odin Project's Foundations course if you want a stronger foundation. Both are free. Both are excellent. AlgoInsight has its own JavaScript course (called JavaScript by FAANG Engineers) which I'd point you at if you want the polished version, but the free options work.
Not a weekend bootcamp. If you finish in a weekend, you didn't do the exercises. The exercises are where the learning happens. Don't skip them.
Not a framework tour. I'll teach Express deeply because it's the lingua franca. I'll touch Fastify, Koa, NestJS, and Hapi enough to let you choose between them. But I'm not going to walk you through every plugin in the ecosystem - that's reference work, and there are better sources for it once you know what to look for.
Not exhaustive on the npm ecosystem. I'm going to teach you the package model, semver, lockfiles, common patterns. I'm not going to review every popular npm package. The ecosystem moves too fast; anything I review today is replaced in two years.
What I Expect From You
Consistency over intensity. An hour a day, four days a week, will get you further than ten-hour weekend benders. The course is dense; your brain needs sleep to consolidate.
Type the code. Don't copy-paste. The first time through a concept, type it out. You'll catch the small things that copy-paste hides - the trailing comma, the missing await, the wrong import path. These small things are 80% of being a Node engineer.
Read the references. Each lesson ends with a short list of references - the official docs section that's relevant, sometimes a talk video, sometimes a blog post that explains something better than I can. If I link it, I think it's worth your time.
Do the exercises. Especially the stretch exercises. The warmup ones are confidence checks. The core ones drill the concept. The stretch ones are where senior engineers are made.
Ask honest questions. If something doesn't make sense, don't power through. Note it. Re-read the section. If it still doesn't click, post in the AlgoInsight Discord (Arun runs it; I drop in regularly). Confused questions from real students are how I improve the course over time.
Why I'm Teaching This Specifically
I want to be honest with you about why I'm here.
I get asked to write Node content reasonably often. There are well-paying contracts attached to Node tutorials on YouTube and elsewhere. I've turned most of them down. The Node content space is full of three-hour videos by people whose Node experience is the tutorial they're filming, and I don't want to add to that pile.
I said yes to this course because AlgoInsight let me build it the way I wanted. Specifically:
- I can go deep on internals (Module 3) without a sales team telling me it's too technical.
- I can speak in my own voice instead of a sanitized tutorial-narrator voice.
- I can have opinions and defend them.
- The course can take a year to build out properly without anyone pressuring a shortcut.
This is the course I wish someone had handed me when I was sitting in a Warsaw café in 2018 trying to understand why my Node server kept crashing on a EADDRINUSE error. It exists now. You don't have to figure that out alone.
Let's get to work.
Try It
Exercise: Warmup (5 minutes). Open a notebook (digital or paper). Write one sentence answering: Why do you want to learn Node.js? Be specific. "I want a backend job" is fine. "I want to build the API for my side project" is fine. "I'm not sure yet, but I'm curious" is fine. What's not fine is "to learn Node.js" - that's circular. The answer doesn't need to be permanent, just honest. You'll come back to it after Module 5 and again after Module 25.
Exercise: Core (10 minutes). Find one Node.js application running on a computer you have access to right now. Look in the dock or task manager - VS Code itself is a Node.js application (well, Electron, which is Node + Chromium; close enough). So is Slack, Discord, Figma, Notion, Postman, and most other Electron-based desktop apps. The dev tools you've installed (Vite, Webpack, ESLint, Prettier) are all Node.js programs. The point of this exercise: realize Node is already on your machine, doing real work, before you've written a line of code in it.
What's Next
Lesson 1.2 goes back to before Node existed. We'll look at what the web server world looked like in 2008, what specific problem Ryan Dahl was trying to solve, and why his solution had to look the way it did. Without that context, Node.js can feel arbitrary. With it, every design decision makes sense.