Frontend Interview Questions

calendarDec 14, 2025 · 2 min read · frontend interview react vue javascript css web-development  ·
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Comprehensive frontend interview questions covering HTML, CSS, JavaScript, React, Vue, and modern web development practices.

Core Web Technologies

Fundamental concepts every frontend developer should know:

  • HTML & DOM: Document structure, DOM manipulation, semantic HTML
  • CSS: Box model, flexbox, grid, positioning, responsive design
  • JavaScript: ES6+, async/await, closures, prototypes, event loop
  • Browser APIs: Fetch, LocalStorage, Intersection Observer, Web Workers

React

Interview questions covering React fundamentals and advanced patterns:

  • Easy: Components, props, state, hooks (useState, useEffect), lifecycle, Virtual DOM
  • Medium: Context API, useCallback/useMemo, useReducer, reconciliation, keys, CSS-in-JS, Portals, code splitting
  • Hard: Fiber architecture, concurrent features, custom hooks, SSR & hydration, optimistic UI, micro-frontends, performance optimization

Vue.js

Interview questions covering Vue 2, Vue 3, and the Composition API:

  • Easy: Template syntax, directives (v-if, v-for, v-model), components, reactivity basics, Options API vs Composition API
  • Medium: Vuex state management, composables, watchers vs computed, lifecycle hooks
  • Hard: Vue 3 reactivity internals (Proxy-based), advanced composables, performance optimization, SSR

State Management

  • React: Context API, useReducer, Redux, Zustand, React Query
  • Vue: Vuex, Pinia, composables with reactive state

Performance Optimization

  • Code splitting and lazy loading
  • Virtual scrolling for large lists
  • Image lazy loading with Intersection Observer
  • Web Workers for heavy computation
  • Request deduplication and caching
  • Bundle analysis and tree shaking

Advanced Topics

  • Server-Side Rendering (SSR): Hydration, data fetching, Next.js, Nuxt.js
  • Micro-Frontends: Module Federation, independent deployment
  • State Machines: XState, finite state management
  • Forms: Validation, error handling, advanced form libraries
  • Real-time: WebSockets, collaborative editing, Operational Transformation, CRDTs
  • Testing: Unit tests, integration tests, E2E tests

Snippets