Lesson 1.1: What Node.js Actually Is & Runtime Architecture

1. Executive Summary

Node.js is an open-source, cross-platform JavaScript runtime environment built on Google Chrome’s V8 JavaScript engine. It executes JavaScript code outside of a web browser, enabling developers to use JavaScript for server-side scripting, CLI tools, and distributed backend microservices.

2. Architectural Layer Breakdown

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Components:

• V8 Engine: High-performance C++ engine created by Google. Compiles JS into native machine code.
• libuv: Multi-platform C library providing asynchronous I/O based on event loops and a background 4-thread pool.
• C++ Bindings: Connect JavaScript API calls to underlying C/C++ libraries.

3. Hands-On Code Example

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4. Key Takeaways

• Node.js is a runtime environment, not a programming language or framework.
• It leverages single-threaded event-driven execution for I/O operations while utilizing a thread pool for heavy OS operations.