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Table of contents
1.
React Hooks Interview Questions
2.
React Hooks Interview Questions for Freshers
2.1.
1. What is React?
2.2.
2. What are the important features of React?
2.3.
3. What are the advantages of React? 
2.4.
4. What are the limitations of React?
2.5.
5. What do you understand by React hooks?
2.6.
6. What are the benefits of using React hooks?
2.7.
7. Will react hooks work inside the class component? What do you think?
3.
React Hooks Interview Questions for Intermediate
3.1.
1. What is the Virtual DOM?
3.2.
2. What are the differences between class components and functional components?
3.3.
3. What do you know about React props?
3.4.
4. What do you understand by React state?
3.5.
5. What is the difference between state and props in React?
3.6.
6. What is the use of useState() in React Hooks?
3.7.
7. What is the use of useEffect in React Hooks?
3.8.
8. What is the use of useRef in React Hooks?
3.9.
9. What is the use of the useCallback hook?
3.10.
10. What is the use of the useMemo hook?
4.
React Hooks Interview Questions for Experienced
4.1.
1. Why were Hooks introduced in React?
4.2.
2. Name the rules that must be followed while using React Hooks.
4.3.
3. Why do React Hooks make use of refs?
4.4.
4. What do you know about the Custom Hooks?
4.5.
5. Below we have a class component with a state value
4.6.
how can you rewrite this component using react hooks?
4.7.
6. How can you update the current state value based on the previous state value using react hooks?
4.8.
7. You are given a code snippet in the form of a class component that registers and removes an event listener.
4.9.
Can you rewrite this using the react hooks?
5.
Conclusion
Last Updated: Jun 12, 2024
Medium

Top React Hooks Interview Questions

Author Aniket Majhi
2 upvotes
Create a resume that lands you SDE interviews at MAANG
Speaker
Anubhav Sinha
SDE-2 @
12 Jun, 2024 @ 01:30 PM

Hello and welcome, readers! We hope you are doing great.

So, you are preparing for your upcoming React Hooks Interview. Are you getting nightmares about the React Hooks Interview Question? Or you are confused about where to prepare for the React Hooks Interview Questi

Don't worry. You have come to the right place. Coding Ninjas is there to help you out. Here in this article, we have crafted the Top React Hooks Interview Questions for you. 

react hooks interview questions

React Hooks Interview Questions

This article will make you confident before appearing for your upcoming React Hooks Interview and will help you extend your knowledge regarding the fundamental concepts of React Hooks. So leave all your worries and follow this article till the end to ace your next React Hooks Interview Questions.

To learn more about React, follow this course, React.js.

Now, Without any further ado, let's start discussing some Top React Hooks Interview Questions.

React Hooks Interview Questions for Freshers

1. What is React?

React is an efficient, flexible, open-source front-end javaScript library created by FaceBook in 2011. It is a tool for building complex and reusable user interfaces, especially for single-page applications. It follows the component-based approach.

2. What are the important features of React?

The following are React's important features:

  • It supports server-side rendering.
  • It follows the component-based approach.
  • It follows unidirectional data flow.
  • It uses Virtual DOM rather than real DOM.
  • React uses JSX, a combination of basic HTML and JavaScript.

3. What are the advantages of React? 

The advantages of React are as follows:

  • Easy to Learn and Use: React is easy to learn and use, as it uses JSX, a combination of basic HTML and JavaScript with some addition.
     
  • Reusable Components: React follows the components-based approach to building mobile and web applications, and an application consists of multiple components. You can reuse these components throughout the application.
     
  • Unidirectional Data Flow:  React follows the unidirectional data flow while designing a react app. It becomes easier to debug errors and identify where the problem occurs.
     
  • Use of Virtual DOM:  React uses the Virtual DOM instead of Real DOM. Virtual DOM compares the component's previous states and updates only the changed items in Real DOM instead of updating all the components again. Thus it makes the web application faster.
     
  • SEO Friendly: React allows server-side rendering, which boosts the SEO of an application.

4. What are the limitations of React?

Following are the limitations of React:

  • The first thing is that React is not a fully-fledged framework. It is just a JavaScript library.
  • The beginner programmer might face difficulties understanding React fully.
  • There are numerous components in React, which might take time to grasp all the benefits fully.
  • The coding might become complex using JSX.

5. What do you understand by React hooks?

Hooks are the newly added features in React v16.8. They are in-built functions that allow the developers to use state and life cycle methods within the components in React. They allow you to use all React features without writing a class component. Using Hooks, we can extract the stateful logic from a component so it can be tested independently and reused. This makes it possible to share Hooks among many components.

6. What are the benefits of using React hooks?

Following are some of the benefits of using React Hooks:

  • If you use React Hooks, you can code in React without using classes.
  • You can easily test and reuse existing states in your code using hooks.

7. Will react hooks work inside the class component? What do you think?

No, react hooks won’t work inside the class component.

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React Hooks Interview Questions for Intermediate

1. What is the Virtual DOM?

The Virtual DOM in react a concept, where a virtual representation of the real DOM is kept inside the memory and is synced with the real DOM by a library such as ReactDOM.

2. What are the differences between class components and functional components?

The differences between the class component and functional component are as follows:-

PointsFunctional ComponentsClass Components
DeclarationThese are nothing but JavaScript Functions. So, you declare it in the same manner as the JavaScript function.On the other hand, class components are declared using the ES6 class.
Handling PropsHandling props is very straightforward. You can use any prop as an argument to a functional component that can be directly used inside HTML elements.For class components, the props are handled differently. Here, we make use of the “this” keyword.
Handling StateFunctional components use react hooks for handling state.For the class components, we can't use the hooks, so for this case, for handling the state, we make use of a different syntax.
ConstructorFor the functional components, constructors are not used.For the class components, constructors are used for storing the state.
Render MethodIn the functional component, there is no use of the render() method.In the class component, it must have the render() method.

3. What do you know about React props?

In react, the prop stands for "Properties". They are plain JavaScript objects. Every React Component accepts a single object argument, known as the props. You can pass these props from one component to another using HTML attributes, and the accepting components accept these props as an argument. One thing to note is that props are immutable, which means they can be changed or manipulated inside a component.

Also check: oop interview questions

4. What do you understand by React state?

In React, the states are plain JavaScript objects. The state is used to contain data or information about the component. The state of a component can change over time. Whenever the state changes, it re-renders.

5. What is the difference between state and props in React?

Both the state and props are JavaScript objects. They are different in their functionality regarding the component.

StateProps
States are managed within the component, similar to variables declared within a function.Props get passed to the component similar to function parameters.
State is mutable(that is it can be modified).Props are immutable(that is they cannot be modified).
You can read as well as modify states.Props are read-only.

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

useState is one of the built-in React hooks. It allows you to track the state in a functional component in React. The term state refers to data or properties that need to be tracked. You need to pass the initial state inside the useState(), which returns variables with the state value and another function to update the current state of the variable.

7. What is the use of useEffect in React Hooks?

useEffect is one of the built-in React Hooks. It allows you to manage side effects in your functional components in React. Here the term side effects refer to fetching requests, manipulating DOM, using timer functions and more.
The useEffect accepts two arguments a callback function and dependencies. The callback function contains the side effects, while the dependencies are optional. If the value of the dependencies has changed between the rendering, then only useEffect() to execute the callback function.

8. What is the use of useRef in React Hooks?

useRef is one of the built-in React Hooks. It allows you to persist values between render. You can also use it to store a mutable value that does not cause a re-render when updated. You must pass the initial value inside the useRef, which returns a mutable ref object. The object has a property called "current", where the value is persisted.

9. What is the use of the useCallback hook?

useCallback is one of the react hooks used to prevent functions declared within the body of function components from being recreated on every render.

10. What is the use of the useMemo hook?

The useMemo hook is used to memoise an expensive operation that we give it. The term "memoise" refers to remembering past values that have already been computed.

React Hooks Interview Questions for Experienced

1. Why were Hooks introduced in React?

The main reason for introducing React Hooks was to make the functional components stateful. Before React v16.8, the functional components were called stateless components as we could only do the state management and the life cycle methods using only the class components. So whenever we needed to use the state management or life cycle methods, we had to change the functional components to the class components.

2. Name the rules that must be followed while using React Hooks.

The rules that must be followed while using React Hooks are mentioned below:

  • You can only call the React Hooks from the react functional components.
  • React hooks must only be called at the top level. They should not be called inside nested functions, loops or conditions.

3. Why do React Hooks make use of refs?

Following are some of the reasons for using refs in React Hooks:

  • Managing focus, media playback or text selection.
  • Integrating with DOM libraries by third-party.
  • Triggering the imperative animations.

4. What do you know about the Custom Hooks?

Custom Hooks in react is a JavaScript function whose name starts with "use", and they may call other Hooks.

5. Below we have a class component with a state value

 

class Count extends Component {
    state = {
      value: 0,
    };
 
    incrementValue = () => {
      this.setState({
        value: this.state.value + 1,
      });
    };
 
    render() {
      return (
        <div>
          <button onClick={this.incrementValue}>Count:{this.state.value}</button>
        </div>
      );
    }
  }

how can you rewrite this component using react hooks?

The equivalent code using function component and react hooks are shown below,

import React, { useState } from "react";

const Count = () => {
 const [value, setvalue] = useState(0);

  return (
    <div>
      <button
        onClick={() => {
          setCount(value + 1);
        }}
      >
        Count: {value}
      </button>
    </div>
  );
}

6. How can you update the current state value based on the previous state value using react hooks?

Thing is that you can update the current state value by passing the new value to the update function or by passing a  callback function. The second technique is safe to use. 

Below, is the code for updating the current state value based on the previous state.

import React, { useState } from "react";

const Count = () => {
 const [value, setValue] = useState(0);

 const increment= () => {
   setCount((prevValue) => {
     return prevValue + 1;
   });
 };

 const decrement = () => {
   setCount((prevValue) => {
     return prevValue - 1;
   });
 };

 return (
   <div>
     <strong>Count: {value}</strong>
     <button onClick={increment}>Increment</button>
     <button onClick={decrement}>Decrement</button>
   </div>
 );
}

7. You are given a code snippet in the form of a class component that registers and removes an event listener.

componentDidMount() {
window.addEventListener("mousemove",this.handleMousePosition);
}

componentWillUnmount() {
  window.removeEventListener("mousemove",this.handleMousePosition);
}

Can you rewrite this using the react hooks?

 The react-hook version of the code is shown below,

useEffect(() => {
   window.addEventListener("mousemove", handleMousePosition);

   return () => {
    window.removeEventListener("mousemove",handleMousePosition);
   };
}, []);

Conclusion

In this article, we have extensively discussed the Top React Hooks Interview Questions. We started with the basic introduction and discussed some important Top React Hooks Interview Questions generally asked in interviews.

We hope this blog gives you some ideas regarding Top React Hooks Interview Questions. If you want to learn more, follow our articles Important Node Js Interview Questions, System Design Interview Questions, Selenium Interview Questions ,Managerial Round Interview Questions, DBMS Interview QuestionsTop Spring MVC Interview Questions and HTML Interview QuestionsYou can also consider our React Js Course to give your career an edge over others.

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