The Top Fifteen React JS Interview Questions

Top 15 React JS Interview Questions

React JS is currently the fastest-growing framework that is used for developing an application or a website. The following are some of the top interview questions related to React JS that will give the applicant an idea about the technology.

What is React JS?

It is a front-end JavaScript library that is used for building web and mobile user interfaces. It allows developers to create and build reusable UI components.

What are the React components?

React components are defined as the building materials which are used by React to create websites and application UIs. Components help break down the UI into reusable parts, which helps in improving React's performance speed.

What is JSX?

It is defined as the syntax extension of JavaScript. It is used with React in order to define the user interface and how it should look.

What are the limitations of React?

React has the following limitations:

  • It is just a library and not a complete framework.
  • It had a huge library that takes time to understand.
  • For a new or new programmer, it’s difficult to understand.
  • It makes coding more complex because of the use of inline templating and JSK.

Do you have a definition for virtual DOM?

It is a document object model that represents an HTML document with a logical tree structure. A Virtual DOM is the representation of the real DOM in memory. When an object changes, the virtual DOM changes only those objects in the real DOM rather than updating all of them.

Why can't browsers read JSK?

Web browsers cannot read JSK directly because they are meant to read only regular JS objects, and JSK is not a regular JS object.

How is React different from Angular?

React is different from Angular in different contexts, such as in architecture. React is only the view of MVC while Angular is a complete MVC. Similarly, React focuses on server-side rendering while Angular focuses on client-side rendering, and React uses virtual DOM while Angular makes use of real DOM.

What is the difference between the ES6 and ES5 standards?

The ES6 and ES5 standards are different from each other on the grounds of:

  • Components and functions:
  • Exports and exports
  • import and require

What is an event in React?

An event is defined as the action that a user or system may trigger, such as a mouse click, a pressure key, etc. Using JSK, a function is taken as the event handler in place of a string in HTML.

Explain the distinction between Props and State.

State is the default data value used in a React component that can be easily changed over time, while Props is the description given to the way a React component is configured. Props do not get changed over time.

When is a class component used over a functional component?

Functional components are the most basic type of React components, also known as props components, whereas class components are more complex components that allow developers to execute component lifecycle methods. Class components are used over functional components when there is a need to manage a state or use component lifecycle methods.

What is REDUX?

It is defined as a library that is compatible with React and helps developers build web applications that perform consistently. It can be used with React or any other library.

Why did you choose to work with React?

React was chosen as it is easy to learn and start with, and also demonstrates plenty of room for growth. Those who want to grow as React developers will find heaps of opportunities by learning it.

Why is there any need for using keys in lists?

Keys are important because they act as unique identifiers that are used to identify which items have gone through changes or updates. Also, it helps in identifying which components are calling for re-rendering.

What is an arrow function and how is it used in React?

An arrow function is a short method used for writing a function in React. While using it, it is unnecessary to use ‘this’ inside the constructor.

Go through the above questions and sharpen your skills with React JS to clear the interview.

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