JavaScript, TypeScript and React — Questions¶

This file tracks big-picture, cross-module questions about JavaScript, TypeScript, and React. For questions specific to a single module, use that module's QUESTIONS.md instead.

How to Use This File¶

1. Write questions immediately — when something is confusing, log it here before moving on.
2. Be specific — "I don't understand closures" is less useful than "Why does a closure still hold a reference to a variable after the outer function returns?"
3. Update status as you find answers — partial answers count.
4. Link your answers to the module or resource where you found the explanation.
5. Add follow-up questions — good answers often raise better questions.

Status Legend¶

Question Format¶

### Q{{N}}: {{QUESTION_TITLE}}

**Asked:** {{YYYY-MM-DD}}
**Status:** 🔴 Unanswered

**Full question:**
Write the question in full. Include context about what prompted it.

**My current hypothesis:**
What do you think the answer might be, even if you're not sure?

**Answer:**
_To be filled in_

**Source:**
_Where did you find/confirm the answer?_

**Follow-up questions:**
- _Any new questions this answer raised_

Questions¶

Q001: When should I use TypeScript instead of plain JavaScript?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: TypeScript adds types but also adds complexity (tsconfig, build step, type errors). Is it always worth it? Are there cases where plain JavaScript is a better choice?

My current hypothesis: TypeScript seems better for large teams and large codebases. Maybe JavaScript is fine for small scripts and prototypes?

Answer: To be filled in

Source: To be filled in

Follow-up questions: - How hard is it to add TypeScript to an existing JavaScript project? - Does TypeScript actually catch real bugs in practice, or is it mostly documentation?

Q002: What is the difference between React and a full framework like Angular or Vue?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: React is called a "library" not a "framework". What does that actually mean in practice? What does React not provide that a framework like Angular provides?

My current hypothesis: React handles the UI rendering part only. Things like routing and data fetching require separate libraries, which gives more flexibility but also more choices to make.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - Is the React ecosystem (React + Router + React Query + Vite) collectively a framework? - When would I choose Vue or Angular over React?

Q003: How does the JavaScript event loop actually work?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: JavaScript is single-threaded but handles async code. How does it actually do this without blocking? What is the difference between the task queue and the microtask queue?

My current hypothesis: I think the browser runs timers and network requests in the background and then calls our callbacks when done. But I don't understand the ordering rules.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - Why do Promise callbacks always run before setTimeout callbacks, even with setTimeout(fn, 0)? - How does React's batched state updates interact with the event loop?

Q004: What are React hooks and why did they replace class components?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: I keep seeing references to "before hooks" and "after hooks". What problem did hooks solve? Why can't you use hooks inside conditions or loops?

My current hypothesis: Hooks make it easier to share stateful logic between components. Class components required patterns like HOCs and render props that were confusing.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - Are class components deprecated or just discouraged? - What does React internally use to track hook call order?

Q005: What is the difference between SSR, SSG, and CSR in the context of Next.js?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: Next.js supports Server-Side Rendering, Static Site Generation, and Client-Side Rendering. When should I use each? What are the performance and SEO tradeoffs?

My current hypothesis: SSG is fastest for content that doesn't change. SSR is needed for dynamic content that changes per user. CSR is the default React model but bad for SEO.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - What is ISR (Incremental Static Regeneration) and how does it fit in? - What are React Server Components and how do they differ from SSR?

Add new questions above this line. Keep them numbered sequentially.

Resolved Questions Archive¶

Move fully answered questions (🟢) here to keep the active list manageable.

(none yet)

Question Stats¶