React js Interview questions

React js Interview questions | Freshers & Experienced

  • Calvin
  • 12th Apr, 2021

Key Features of React Js

Below are few major features of React Js

One-way Data Binding


Virtual DOM

JavaScript Syntax Extension



Lifecycle Methods

React js Interview Questions

Q1. Can React be used without JSX?

Q2. What is difference between MVC and Flux?

Difference between MVC and Flux

MVC (Model view controller) and Flux both are design patterns used for web development. Because of MVC’s simplicity, it is considered as the most used form of web design.

Flux is a completely new architecture with a different concept from social media Facebook and works in a unidirectional concept.

Q3. Explain the difference pure components and general components in React?

Q4. What are Higher Order Components (HOC) in React?

Higher-order components are a pattern that rises up from React’s nature of the composition. HOC is a new technique used for reusing the logic.

Basically, HOC will take the old component and returns the new component.

Q5. Explian the events lifecycle of React?

The components of React are functions also classes. When the programmer uses the methods on classes or functions are called as lifecycle events.

There are three stages of lifecycle events.

  • Mounting: During the mounting phase, the component is created and inserted into the DOM.
  • Updating: When a component is updated, the component is rendered.
  • Unmounting: The same component when is it removed from the DOM is called as Unmounting.

Q6. What is difference between functional and class components in React?

Q7. Why do we need a Redux with React?

Q8. What is flux?

Flux is a type of architecture or pattern used by Facebook internally when it is working along with React. This is not a library or a type of framework. But a simple and new type of architecture and one which complements React along with the concept of Unidirectional Data Flow. The individual components of Flux that will help in understanding it better are mentioned below:

  1. Action
  2. Store
  3. Dispatcher
  4. Controller View

Q9. Explain the difference between prop and state in ReactJs?

Q10. How to set up routing in ReactJS?

Q11. What are stateless and stateful components in React?

Stateless and stateful components in React

Stateless components are also a functional component in which the local state is absent. But the state characteristics can be added in addition by React.

Stateful components are the exact opposite of stateless components by having a local state into it. It has the state object and sometimes, event handling functions also.

Q12. What are synthetic events? How do they differ from non-synthetic events?

Q13. What are refs? Why would we need them?

Q14. What is diffing in React Js?

Diffing is a process of comparing the current version of DOM with its previously done DOM. This action of comparing is done by React. When react observes the state changes, it immediately captures the change and update in the virtual DOM tree. With this available data, React’s responsibility is to compare.

Q15. What React.createElement() method does?

Q16. How to start development server in ReactJs?

Q17. What is use of super method in React?

Q18. What is Babel?

Babel is a compiler of Javascript. It is an open-source as well as a free compiler. The main purpose of this compiler is to convert the code of ECMAScript 2015+ into a code that is backward-compatible one of the Javascript only and can also be executed easily on earlier engines of Javascript. This is a well-known tool to use the latest features of the well-renowned programming language of Javascript.

Q19. What is Factory Design Pattern?

The factory design pattern is a type of creational design method. This method is related to the creation of an object. In this pattern, objects are created without the creation of logic being exposed to the client. The client also uses the same interface which is quite common, to create an object of a new type. The intention is to use the static member function, this will create and return the instances, without exposing the details to the user of the class modules.

Q20. What are angular2 directives?

About Author :

  • Author of React js Interview questions

    Calvin Carlo

    Calvin is a Senior web developer, a Javascript enthusiast, and a technical writer. He is very interested in learning new technologies and writing technical blogs on It. He loves playing Cricket, watching Hollywood action movies and is big fan of Michael Douglas.

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