React Interview Questions For Experienced
Here, we cover advanced react interview questions with answers for experienced professionals, who have over 5+ years of experience.
36. What is custom hooks in React?
Custom hooks are normal JavaScript functions whose names start with “use” and they may call other hooks. We use custom hooks to maintain the DRY concept that is Don’t Repeat Yourself. It helps us to write a logic once and use it anywhere in the code.
We can improve our react code by following these practices:
- Using binding functions in constructors
- Eliminating the use of inline attributes as they slow the process of loading
- Avoiding extra tags by using React fragments
- Lazy loading
38. What is the difference between useref and createRef in React ?
useRef | createRef |
|---|---|
| It is a hook. | It is a function. |
| It uses the same ref throughout. | It creates a new ref every time. |
| It saves its value between re-renders in a functional component. | It creates a new ref for every re-render. |
| It returns a mutable ref object. | It returns a read-only ref object. |
| The refs created using the useRef can persist for the entire component lifetime. | The refs created using the createRef can be referenced throughout the component. |
| It is used in functional components. | It is used in class components. |
39. What is react-redux?
React-redux is a state management tool which makes it easier to pass these states from one component to another irrespective of their position in the component tree and hence prevents the complexity of the application. As the number of components in our application increases it becomes difficult to pass state as props to multiple components. To overcome this situation we use react-redux
They are several benfits of using react-redux such as:
- It provides centralized state management i.e. a single store for whole application
- It optimizes performance as it prevents re-rendering of component
- Makes the process of debugging easier
- Since it offers persistent state management therefore storing data for long times become easier
There are four fundamental concepts of redux in react which decide how the data will flow through components
- Redux Store: It is an object that holds the application state
- Acrtion Creators: These are unctions that return actions (objects)
- Actions: Actions are simple objects which conventionally have two properties- type and payload
- Reducers: Reducers are pure functions that update the state of the application in response to actions
42. How can we combine multiple reducers in React?
When working with Redux we sometimes require multiple reducers. In many cases, multiple actions are needed, resulting in the requirement of multiple reducers. However, this can become problematic when creating the Redux store. To manage the multiple reducers we have function called combineReducers in the redux. This basically helps to combine multiple reducers into a single unit and use them.
Syntax:
import { combineReducers } from "redux";
const rootReducer = combineReducers({
books: BooksReducer,
activeBook: ActiveBook
});
43. What is context API?
Context API is used to pass global variables anywhere in the code. It helps when there is a need for sharing state between a lot of nested components. It is light in weight and easier to use, to create a context just need to call React.createContext(). It eliminates the need to install other dependencies or third-party libraries like redux for state management. It has two properties Provider and Consumer.
44. Explain provider and consumer in ContextAPI?
A provider is used to provide context to the whole application whereas a consumer consume the context provided by nearest provider. In other words The Provider acts as a parent it passes the state to its children whereas the Consumer uses the state that has been passed.
45. Explain CORS in React?
In ReactJS, Cross-Origin Resource Sharing (CORS) refers to the method that allows you to make requests to the server deployed at a different domain. As a reference, if the frontend and backend are at two different domains, we need CORS there.
We can setup CORS evironment in frontend using two methods:
- axios
- fetch
46. What is axios and how to use it in React?
Axios, which is a popular library is mainly used to send asynchronous HTTP requests to REST endpoints. This library is very useful to perform CRUD operations.
- This popular library is used to communicate with the backend. Axios supports the Promise API, native to JS ES6.
- Using Axios we make API requests in our application. Once the request is made we get the data in Return, and then we use this data in our project.
To install aixos package in react use the following command.
npm i axios
47. Write a program to create a counter with increment and decrement?
import React, { useState } from "react";
const App = () => {
// Counter is a state initialized to 0
const [counter, setCounter] = useState(0)
// Function is called everytime increment
// button is clicked
const handleClick1 = () => {
// Counter state is incremented
setCounter(counter + 1)
}
// Function is called everytime decrement
// button is clicked
const handleClick2 = () => {
// Counter state is decremented
setCounter(counter - 1)
}
return (
<div>
<div>
{counter}
</div>
<div className="buttons">
<button onClick={handleClick1}>
Increment
</button>
<button onClick={handleClick2}>
Decrement
</button>
</div>
</div>
)
}
export default App
It is advised to use a callback-based approach to update the state using setState because it solves lots of bugs upfront that may occur in the future.We can use the following syntax to update state using callback
this.setState(st => {
return(
st.stateName1 = state1UpdatedValue,
st.stateName2 = state2UpdatedValue
)
})
49. What is React-Material UI?
React Material UI is a framework leveraging React library, offering prebuilt components for creating React applications. Developed by Google in 2014, it’s compatible with JavaScript frameworks like Angular.js and Vue.js. Renowned for its quality designs and easy customization, it’s favored by developers for rapid development.
Flux is AN architecture that Facebook uses internally when operating with React. It is merely a replacement quite an architecture that enhances React and also the idea of unidirectional data flow.
Conclusion
This compilation of React Interview Questions and Answers covers a wide range of topics, from basic concepts to advanced techniques. Whether you’re a beginner or an experienced developer, mastering these questions will enhance your readiness for React interviews and boost your confidence.
For further reading, check out our dedicated article on Advanced ReactJS Intermediate Interview Questions. Inside, you’ll discover over 20 questions with detailed answers.
React Interview Questions and Answers
React is an efficient, flexible, and open-source JavaScript framework library that allows developers to the creation of simple, fast, and scalable web applications. Jordan Walke, a software engineer who was working for Facebook created React. It was first deployed on the news feed of Facebook in 2011 and on Instagram in 2012. Developers from the Javascript background can easily develop web applications with the help of React. It is a component-based front-end library responsible only for the view layer of an MVC (Model View Controller) architecture. It is an important language for aspiring front-end developers. React is used by top IT companies such as Facebook, Dropbox, Instagram, WhatsApp, Atlassian, and Meta because of its Virtual DOM, Components, State and Props, JSX, Hooks, and Routing. So, to get into these companies, you need to complete these Top React interview questions which can make you seem like an expert in front of the interviewer.
In this Top React Interview Questions article, we’ve covered the Interview Questions of React that cover everything from basic to advanced React concepts such as Virtual DOM, Components, State and Props, JSX, Hooks, Routing, and more. Whether you are a fresher or an experienced professional with 2 – 10 years of experience, these React Interview Questions give you all the confidence you need to ace your next technical interview.
ReactJS Interview Questions and Answers
Table of Content
- React Interview Questions For Freshers
- React Intermediate Interview Questions
- React Interview Questions For Experienced