Easy everything in Node.js & Express, page 4
__dirname and __filename: Path Anchors in Node.js
__dirname and __filename act as GPS for your Node.js files, giving you the absolute path to the current file and its directory. This is essential for reliably loading adjacent files, like templates or configs. The main gotcha: they don't exist in ES Modules.
Node.js File I/O: Synchronous vs. Asynchronous
Synchronous file I/O blocks your app, like waiting at a counter for your order. Asynchronous I/O gets a buzzer, letting your app work on other tasks. Use async for servers and sync for simple, one-off scripts. The footgun is using sync I/O in a server.
Creating a Basic HTTP Server in Node.js
A Node.js HTTP server is a listening post that waits for requests on a port and runs your code to reply. It's the foundation for any web service, from simple APIs to full apps. The footgun: forgetting response.end() leaves the client hanging indefinitely.
JavaScript Promises: Handling Future Values
A Promise is an IOU for a future value from an async operation. Instead of blocking your code, you get an object that will eventually contain the result or an error. They're essential for API calls or file reads.
npm Scripts: Your Project's Command-Line Shortcuts
Think of npm scripts as aliases for your project's common command-line tasks, stored in package.json. Use them to run build tools, start servers, or execute tests. The main footgun is forgetting npm run for custom scripts like lint or build.
Dependencies vs. DevDependencies: What's the Difference?
Dependencies are packages your app needs to run in production (like a web framework). DevDependencies are for your development workflow (like a test runner). The footgun is mixing them up, which bloats your production build with unnecessary code.
package.json: The Blueprint for Your Node.js Project
The package.json file is the blueprint for a Node.js project, listing its dependencies and runnable scripts. It's essential for installing libraries (npm install) and running tasks (npm test).
CommonJS: Node.js's Original Module System
CommonJS treats each file as a private box of code. You share tools using exports and import them with require. It's the original module system for Node.js, used to organize code into reusable pieces.
Node.js Events and the EventEmitter
Node.js handles concurrency with an event-driven model, not threads. "Emitters" fire named events that "listeners" react to, enabling non-blocking I/O for things like file reads and web requests.
V8: The Engine Powering Chrome and Node.js
V8 is the engine that runs your JavaScript, translating it into machine code. It powers both the Chrome browser and the Node.js server-side runtime. The common footgun is confusing the engine (V8) with the runtime environment that provides it with APIs.
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