WebApp using Node.js

Fast and Scalable

Event-driven architecture and non-blocking I/O API from ground-up

• Model best for slow/blocking (network) I/Os, now asynchronously handled
• Resource efficient. Can easily scale up with Cloud Services
• Support asynchronous programming (but Node operates on single-thread event loop)

Code reuse due to single language across both client and server side -> (Non-)Developer-friendly

• JIT Compilation (ref in L3): Compiled to binary, and runs like executable ("binds" to libraries in C++)
• Thread pool to handle parallel (non-blocking) I/O tasks ( , )

预览 2025-04-06 21.59.03.png

HTTP is a first class citizen in node () : Built-in HTTP library, doing away with Apache/IIS/Nginx

Event-driven paradigm:

• Create a HTTP server binded to port 3000 of localhost
• Execute the callback per request

NPM

Package Manager: Simplify deployment by auto-resolving dependencies

• A specification standard of (dev)dependencies
• devDependencies 指的是仅在开发期间需要，但不是运行时需要的那些依赖项
• NPM: package.json specifies the required packages
• A repository to host packages published by developers

A CLI toolset to recursively install/manage required dependencies and versions

• npm install looks for ./package.json, and recursively installs all dependency packages
• npm install <packageName> --save downloads packageName and marks it dependent in your package.json
• npm install <packageName> --save-dev downloads packageName and marks it devDependent in your package.json

npx vs npm exec; run an arbitrary command from an npm package npm exec eslint src/

Packages you will use: express, helmet, cors, csrf, express-session/cookie-session, mysql

Output - HTML vs. JSON

Node/Web Server can simply serve static HTML/CSS/Javascript

• For dynamic content, HTML output is returned after processing

• After users submit the forms via an HTML page, a browser has to re-download the "same" HTML

  page even with a single tiny difference (if you have a large HTML).

Alternative: JavaScript Object Notation (JSON) format

• Compact in response size. Fast JSON parser.
• Facilitate shifting data binding & user-interface (UI) work to client-side

Advantages of using JSON when compared to HTML

• Minimize bandwidth needed (since no redundant download)
• JSON parsing is stunning fast as the format itself is JS (native)!
• Loose coupling: data-intensive processing (Server) and UI handling (Client)