React is a popular front-end JavaScript library that is widely used to develop highly interactive user interfaces for web applications. As React is becoming more popular, the demand for React developers is increasing, and many companies are hiring developers with expertise in React.
If you are preparing for a React interview, you might be wondering what questions you should expect. Here are 20 of the most important and most commonly asked React developer interview questions, along with detailed answers to help you prepare.
What is React?
React is a JavaScript library that is used to build user interfaces for web applications.
What are the benefits of using React?
React offers several benefits, including improved performance, code reusability, and ease of development.
What is JSX?
JSX is a syntax extension to JavaScript that allows developers to write HTML-like code in their JavaScript files.
What is a component in React?
A component is a reusable piece of code that defines the behavior and appearance of a part of a user interface.
What is the difference between a functional component and a class component in React?
A functional component is a stateless component that is written as a function, while a class component is a stateful component that is written as a class.
What is state in React?
State is a JavaScript object that stores the data that a component needs to render its user interface.
What is props in React?
Props (short for “properties”) are a way to pass data from a parent component to a child component in React.
What is the difference between state and props in React?
State is used to store data that is local to a component, while props are used to pass data from a parent component to a child component.
What is the role of ReactDOM in React?
ReactDOM is a library that provides an interface for rendering React components to the DOM.
What is the virtual DOM in React?
The virtual DOM is a lightweight copy of the actual DOM that React uses to track changes to a component’s state and to update the actual DOM more efficiently.
What is the lifecycle of a React component?
The lifecycle of a React component consists of several phases, including mounting, updating, and unmounting.
What is the difference between the componentDidMount and componentDidUpdate lifecycle methods?
The componentDidMount method is called once after a component is mounted to the DOM, while the componentDidUpdate method is called after a component is updated.
What is the shouldComponentUpdate method?
The shouldComponentUpdate method is a lifecycle method that determines whether a component should be updated based on changes to its state or props.
What is the difference between controlled and uncontrolled components in React?
A controlled component is a component that has its value controlled by React, while an uncontrolled component is a component that manages its own value.
What are refs in React?
Refs are a way to access the properties of a component directly, without going through its props or state.
What is the React Router?
The React Router is a library that allows developers to implement routing and navigation in a React application.
What is Redux?
Redux is a library that is used to manage the state of a React application.
What is the Flux architecture?
The Flux architecture is a pattern for managing the state of a React application, which involves a unidirectional flow of data.
What is the difference between Redux and Flux?
Redux is a library that is based on the Flux architecture, but it simplifies some of the concepts and adds some additional functionality.
What are actions in Redux?
Actions are plain JavaScript objects that represent an event that has occurred in a React application.
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