Node.js Lecture Notes

Introduction to Node.js

Node.js (Node): An open-source, cross-platform runtime environment for executing JavaScript code outside a browser.
Usage: Predominantly used to build backend services (APIs) that power client applications like web apps in browsers or mobile apps.
Ideal For: Building highly scalable, data-intensive, and real-time backend services.

Ease of Use: Easy to get started with and suitable for prototyping and agile development.
Performance: Can build fast, scalable services used by companies like PayPal, Uber, Netflix, and Walmart.
- Example: PayPal moved from Java/Spring to Node, resulting in faster builds and better performance.
JavaScript Reuse: Node.js uses JavaScript, so front-end developers can transition to full-stack developers easily.
Consistency: Using JavaScript on both the front and backend makes source code cleaner and more consistent.
Ecosystem: Largest ecosystem of open-source libraries, allowing reuse of existing solutions.

Runtime Environment: Node is a runtime environment similar to a browser environment but for server-side applications.
- Uses V8, Chrome's JavaScript engine, to run JavaScript outside the browser.
- Provides different objects compared to browser environments (e.g., no window or document objects).
Non-blocking Architecture: Asynchronous, meaning single-threaded handling of multiple requests without waiting (non-blocking I/O).
- In contrast to synchronous/blocking architectures that require multiple threads.
Event-Driven: Uses events to handle operations asynchronously.

Event Emitter: Core to Node's event handling, allowing objects to emit events and handle them with listeners.
Examples: http module uses events to notify about server connections or requests.

HTTP Module: Used to create networking applications like web servers.
File System (fs) Module: For working with files and directories. Supports both synchronous and asynchronous operations (prefer async for non-blocking operations).
Path Module: Provides utilities for working with file and directory paths.
OS Module: Used to retrieve information about the operating system (e.g., total/free memory).

Modules: Every Node.js file is a module. Variables and functions are scoped to the module, not the global environment.
Exporting: Functions and variables can be exported from a module using module.exports.
Importing: Use require() to import modules.

Creating Servers: Use http.createServer() to create a web server.
Request Handling: Handle incoming requests and serve responses through callbacks.
Express Framework: Often used instead of the raw http module for building structure-friendly applications.

Non-blocking I/O: Node's core feature, enabling the server to handle multiple requests without waiting for operations to complete.
Callback Functions: Used to handle asynchronous operations.

Installation: Available on the Node.js website. Always install the latest stable version recommended for most users.

Code Editors: Visual Studio Code is a popular choice, but others like Sublime Text and Atom can also be used.

Error Handling: Node.js includes mechanisms for handling errors, especially in asynchronous code.
Performance Considerations: Suitable for I/O-bound applications but not CPU-intensive tasks.

Node.js Course Offering: The lecture is part of a larger course on building RESTful APIs with Node.js, covering advanced topics like authentication, testing, and deployment.

These notes provide a comprehensive overview of Node.js, its architecture, advantages, and core functionalities, suitable for review and study.