Fundamentals Interview Questions

See exactly how border-box redefines the width property, why it makes layouts composable, and where it can still bite you.

Understand the four layers every element renders as, and how the two box-sizing modes change what width means.

Understand the three collapsing cases, why parent-child collapsing surprises people most, and the modern ways to stop it.

Learn where each lives in the box model, how their behaviour diverges, and the concrete cases where swapping them breaks a layout.

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 the difference between props and state in React, when to use each, and how they interact to drive rendering.

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 hooks are, the rules that govern them, and how useState and useEffect replace class component state and lifecycle methods.