Quick recall
Many React interviews ask you to reason about UI architecture problems such as search boxes, large lists, debounced input, reusable forms, caching, modal state, theme switching, and optimistic updates.
React components are reusable UI units, and interviews often compare function components, class components, pure components, and presentation-focused designs.
React wraps browser events in SyntheticEvent and uses a consistent event system for handlers like clicks, inputs, and form interactions.
Fiber is React's internal architecture for scheduling and prioritizing work, and StrictMode helps surface unsafe patterns in development.
Class components expose lifecycle methods across mounting, updating, and unmounting phases.
React is a declarative UI library for building component-based single-page applications and interactive interfaces.
React patterns help organize how behavior, layout, and state are shared across components.
React apps become slow when they re-render too much, do expensive work in render, or ship more code and DOM than needed.
Portals let React render children into a DOM node outside the normal parent hierarchy while keeping them in the same React tree.
Safe React code avoids dangerous HTML injection, unnecessary direct DOM manipulation, state mutation, and side effects during render.
React differs from plain DOM code by using declarative rendering, and it differs from Angular or Vue in scope, conventions, and ecosystem philosophy.
Redux organizes state around actions, reducers, a store, and dispatch, and Redux Toolkit is now the preferred modern way to write Redux code.