🧠 Node.js Core & Internals — A Systems-Level Learning Path

Not a framework tutorial. Not a crash course. This repository is a deep, internals-first journey into Node.js, backend engineering, operating systems, networking, performance, and runtime architecture.

If you are here to "learn Express", this repo is not for you. If you want to understand what Node.js really is and how it works under the hood, welcome.

---

🎯 Purpose of This Repository

This repository exists to:

• Understand Node.js as a runtime, not a web framework
• Learn core Node.js modules without relying on external NPM packages
• Build low-level network, file, and streaming systems
• Understand OS, networking, and concurrency concepts behind backend systems
• Learn how Node achieves asynchronous I/O using libuv
• Write high-performance, memory-efficient, scalable backend code
• Read and understand Node.js documentation and source code confidently

This is a learning log + reference + code lab.

---

🧠 Philosophy

Frameworks come and go.
Internals stay forever.

Principles followed in this repo:

• ❌ No Express / Nest / Fastify
• ❌ No unnecessary NPM packages
• ✅ Core modules first
• ✅ Source-code curiosity
• ✅ Performance over convenience
• ✅ Understanding "why", not just "how"

Whenever possible, things are built from scratch using Node core APIs.

---

🗺️ Learning Scope

This repository covers far more than just Node.js:

• Node.js Architecture (V8, libuv, event loop)
• Asynchronous I/O internals
• Operating system fundamentals (processes, threads, syscalls)
• File system internals
• Streams & backpressure
• Networking (TCP, UDP, DNS, HTTP)
• Binary data & buffers
• Cryptography (OpenSSL-backed)
• Multithreading & multiprocessing in Node
• Performance profiling & optimization
• Native C++ addons (N-API)

Think of this as:

Systems Engineering with JavaScript

---

📂 Repository Structure

nodejs-core-internals/
│
├── 00-foundations/
│   ├── js-runtime-notes.md
│   ├── os-basics.md
│   └── unix-notes.md
│
├── 01-node-architecture/
│   ├── architecture.md
│   ├── event-loop.md
│   └── libuv-overview.md
│
├── 02-core-modules/
│   ├── fs/
│   │   ├── fs-notes.md
│   │   └── examples/
│   ├── net/
│   ├── http/
│   ├── stream/
│   ├── crypto/
│   └── ...
│
├── 03-networking/
│   ├── tcp.md
│   ├── udp.md
│   ├── dns.md
│   └── http-deep-dive.md
│
├── 04-streams-performance/
│   ├── streams-internals.md
│   ├── backpressure.md
│   └── large-data-processing.md
│
├── 05-concurrency/
│   ├── event-driven-model.md
│   ├── worker-threads.md
│   └── clustering.md
│
├── 06-binary-and-crypto/
│   ├── buffers.md
│   ├── binary-protocols.md
│   └── cryptography.md
│
├── 07-optimization/
│   ├── performance.md
│   ├── profiling.md
│   └── memory-management.md
│
├── 08-internals/
│   ├── module-loader.md
│   ├── async-hooks.md
│   ├── node-source-guide.md
│   └── cpp-addons.md
│
├── projects/
│   ├── raw-http-server/
│   ├── tcp-chat/
│   ├── stream-compressor/
│   └── worker-thread-pool/
│
└── README.md

---

📦 Core Rule: Core Modules First

Every module used here is from Node.js itself, including but not limited to:

• fs, path, os
• net, dgram, dns
• http, https, tls
• stream, zlib
• buffer, crypto
• events, timers, process
• worker_threads, cluster
• perf_hooks, async_hooks

External packages are only discussed conceptually, never relied on.

---

🧪 How to Use This Repository

1️⃣ Read

Each directory contains Markdown notes explaining:

• Concepts
• Internals
• Why things work the way they do

2️⃣ Code

Every concept is backed by:

• Small experiments
• Minimal examples
• Performance-oriented implementations

3️⃣ Experiment

Break things intentionally:

• Block the event loop
• Exhaust memory
• Flood sockets

Then understand why it broke.

---

🚀 Who This Repo Is For

This repository is ideal for:

• Backend engineers who want real depth
• Security engineers
• Systems programmers curious about Node
• Developers moving beyond frameworks
• Anyone who wants to read Node.js source code

This repo is not beginner-friendly — and that is intentional.

---

📌 Expected Outcome

After completing this repository, you should be able to:

• Explain Node.js architecture confidently
• Build servers without frameworks
• Write memory-efficient streaming systems
• Create TCP/UDP-based applications
• Debug event loop blocking issues
• Profile and optimize Node applications
• Understand how Node interacts with the OS
• Learn any Node.js framework effortlessly

---

⚠️ Disclaimer

This repository is:

• Opinionated
• Internals-focused
• Performance-oriented

It prioritizes understanding over speed and depth over comfort.

---

🏁 Final Words

Most people use Node.js.
Very few understand it.
This repo is for the second group.

Happy Noding 🚀