Fundamentals React Questions

Understand the anatomy of a React function component, how JSX compiles, and the rules that make a valid component.

Understand the key differences between functional and class components, why hooks changed everything, and why functional components are now the standard.

Understand what JSX compiles to, why it exists, and the rules that govern how you write it correctly.

Understand React as a UI library, how its declarative model and virtual DOM work, and why it became the dominant choice for frontend development.

Understand what the virtual DOM is, how it enables efficient updates, and what its real performance tradeoffs are.

Understand the heuristics React uses to compare virtual DOM trees efficiently and how keys enable correct list reconciliation.

Understand how React reconciles the virtual DOM with the real DOM, what triggers re-renders, and how the fiber architecture enables concurrent rendering.