Tools: Week 15 React Learning Recap: Understanding Old React and Finally Respecting useReducer

Understanding Old React Code (Class Components Are a Different World) ## Class Components vs Function Components (The Mental Shift) ## useReducer: The Second Big Learning of This Week ## Final Thoughts This week was not about learning something flashy. It was about understanding how things actually work under the hood. I spent most of this week working with old React code patterns and class components. At the same time, I also started properly learning useReducer, which completely changed how I think about state management. This week felt like a bridge between old React and modern React. This week, I intentionally stepped into pre-hooks React. I built a project called Classy Weather using only class components. The goal was simple: Learn how real old codebases are structured and how they think. Through this, I learned: The most important realization: Class components are not “bad”. They just have a different mental model. Understanding them made me much more confident that I can read and maintain old React projects in real companies. Project: ✅ Classy Weather Before this week, I only used function components. This week, I finally felt the difference. In function components: After writing both styles, I can now clearly say: Hooks are simpler to write. Class components are harder to reason about. But understanding both makes you a much stronger React developer. Alongside class components, I also started learning useReducer. And now I understand why: The course calls it an advanced / pro-level hook. useReducer is not hard because of syntax. It is hard because it forces you to think differently: This week I built a small date counter project using useReducer just to understand: I won’t pretend I’ve mastered it. This week taught me something very important: Not every week is about learning new APIs. Some weeks are about becoming a more serious engineer. I feel like my React foundation is much stronger now. Templates let you quickly answer FAQs or store snippets for re-use. Are you sure you want to hide this comment? It will become hidden in your post, but will still be visible via the comment's permalink. Hide child comments as well For further actions, you may consider blocking this person and/or reporting abuse - How state works in class components - How events are handled in class components - How child-to-parent communication works without hooks - How data fetching is done using lifecycle methods - How componentDidMount and componentDidUpdate replace useEffect - How side effects and localStorage syncing were handled before hooks existed - You think in effects - You think in hooks - You think in state snapshots - You think in lifecycle phases - You think in when to run logic - You think in how state mutates over time - You don’t directly change state - You dispatch actions - A reducer function decides how state changes - All logic lives in one predictable place - Reducer flow - Centralized state logic - The fear is gone - The mental model is clear - And I finally understand why this hook exists - Read old React code - Understand class-based architecture - Respect lifecycle methods - And start thinking in reducers and actions