Over a weekend the author built Classy Weather, a tiny weather widget written entirely with React class components. Having spent recent months only with function components and hooks, the goal was not to add a new feature but to force a deep dive into an old React codebase that still powers many enterprise apps.

The biggest hurdle proved to be translating mental models of hooks into the older lifecycle methods. For example, `useEffect(..., [])` mirrors `componentDidMount`, while a dependency‑driven `useEffect` aligns with `componentDidUpdate`, and its cleanup maps to `componentWillUnmount`. Additionally, class‑based state updates lack functional defaults, demanding careful reasoning about re‑renders.

Finishing the app taught the author that mastering legacy patterns boosts the ability to read and maintain existing codebases, a skill employers value more than any specific syntax. Recognizing where side effects live, how state changes propagate, and the flow of the component lifecycle now feels routine, preparing developers for any future framework shift.