Question inteview Nodejs, Vuejs, Reactjs

Node.js Interview Questions

1. What is Node.js, and how does it work?

   • Explain the asynchronous, event-driven architecture and the use of a single-threaded event loop.

2. What is the difference between setImmediate() and process.nextTick()?

   • Discuss the differences in their execution timing within the event loop.

3. How does the event loop work in Node.js?

   • Explain the phases of the event loop, including timers, I/O callbacks, idle, poll, and check.

4. What is the difference between require and import in Node.js?

   • Talk about module systems, CommonJS (require) vs. ES Modules (import), and when to use each.

5. How do you handle asynchronous operations in Node.js?

   • Discuss callbacks, promises, and async/await.

6. What is middleware in Express.js?

   • Explain how middleware functions work in Express and how they handle requests and responses.

7. What is the purpose of streams in Node.js?

   • Discuss different types of streams (readable, writable, duplex, transform) and how they manage large data efficiently.

8. How does Node.js handle concurrency?

   • Talk about the event loop and how it handles multiple connections asynchronously.

9. What is clustering in Node.js?

   • Explain how to use clusters to improve performance in multi-core systems.

10. What is the role of package.json in a Node.js project?

    • Describe the importance of package.json for managing dependencies, scripts, and project metadata.

Vue.js Interview Questions

1. What is Vue.js, and how does it differ from other frameworks like React or Angular?

   • Highlight Vue’s simplicity, reactivity system, and comparison with React’s virtual DOM and Angular’s structured framework.

2. What are Vue components, and how do you create one?

   • Explain how components are reusable building blocks and demonstrate creating a basic component.

3. What is the Vue reactivity system?

   • Discuss how Vue tracks changes in data using reactive proxies and watchers.

4. How do Vue directives work?

   • Describe common Vue directives like v-if, v-for, v-bind, and v-model.

5. What is Vuex, and why is it used?

   • Explain Vuex as a state management library for centralizing and managing application state in Vue apps.

6. How does Vue handle two-way data binding?

   • Discuss how v-model directive works for synchronizing data between the model and the view.

7. What are mixins in Vue.js, and when would you use them?

   • Talk about using mixins to share functionality across components.

8. What is the Vue Router, and how does routing work in Vue?

   • Explain Vue Router for handling single-page navigation and route components.

9. What are Vue.js lifecycle hooks, and can you name a few?

   • Discuss hooks like created(), mounted(), updated(), and destroyed() and when they are called.

10. What is computed in Vue, and how is it different from methods?

    • Explain how computed properties are cached and reactive, while methods are re-executed on every render.

React.js Interview Questions

1. What is React.js, and how does it differ from traditional JavaScript frameworks?

   • Highlight React’s component-based architecture, virtual DOM, and unidirectional data flow.

2. What is JSX in React?

   • Explain JSX syntax as a blend of HTML and JavaScript, and how it’s transformed into React elements.

3. How does React’s virtual DOM work?

   • Discuss the virtual DOM’s role in efficiently updating only parts of the real DOM that change.

4. What are React hooks, and why are they used?

   • Talk about hooks like useState, useEffect, and useContext for managing state and lifecycle without using classes.

5. What is the difference between a controlled and an uncontrolled component in React?

   • Explain how controlled components are fully managed by React state, while uncontrolled components rely on the DOM.

6. What is the use of useEffect() in React?

   • Describe how useEffect manages side effects (e.g., fetching data, setting up subscriptions) in functional components.

7. How does React manage state?

   • Discuss useState, useReducer, and state lifting for sharing state between components.

8. What is the context API in React?

   • Explain how the context API is used for passing data (like themes, languages) through component trees without props drilling.

9. What is prop drilling, and how do you avoid it?

   • Define prop drilling and explain techniques like using the context API or state management libraries to avoid it.

10. How does React handle performance optimization?

    • Discuss tools like React.memo, useMemo, useCallback, and lazy loading for improving performance.

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