React Interview Questions | ReactJS Interview Questions and Answers | Intellipaat | Summary and Q&A

TL;DR

This article covers important interview questions related to React, including topics such as the DOM, architecture, Redux, stateful components, and more.

Key Insights

• React is a popular front-end technology used for web development, known for its component-based approach and efficiency.
• Virtual DOM is a more efficient and memory-saving alternative to the Real DOM.
• React is used for creating reusable and efficient components, making front-end development simpler.
• JSX is a JavaScript XML syntax used in React to simplify the creation of HTML elements.
• Browsers cannot directly read JSX files; they need to be transformed into JavaScript objects using JSX transformers.
• React has numerous features, including single directional data flow, server-side control, and easy testing.
• Virtual DOM is an exact copy of the Real DOM and is used by React to efficiently update and render components.
• React is widely used due to its efficiency, job opportunities, readability of code, and ability to handle front-end and server-side requirements.

Transcript

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Questions & Answers

Q: Differentiate between controlled and uncontrolled components in React.

Controlled components in React are components where the state and values are managed by React. The data in controlled components is controlled by React and passed down as props. Uncontrolled components, on the other hand, do not have their state managed by React and rely on the DOM for storing and retrieving values.

Q: What are the advantages of using Redux in React?

Redux provides an organized approach to code, making it more consistent and structurally sound. It also simplifies testing, allows for easy tracking of actions, and has a large community for support. Redux also helps manage state and improves overall performance and efficiency in React applications.

Q: How can you conditionally add attributes to components in React?

In React, you can conditionally add attributes to components by using boolean expressions and the ternary operator. If a condition is met, you can include the attribute in the component declaration, and if the condition is not met, you can omit the attribute.

Q: Is there any way to avoid the need for making use of binding in React?

Yes, in React, you can avoid the need for binding by using arrow functions or by utilizing function components with hooks. Arrow functions automatically bind the component's "this" value, while hooks provide a more elegant solution by eliminating the need for binding altogether.

Q: What is the difference between the "getInitialState" and "constructor" methods in React?

In earlier versions of React, the "getInitialState" method was used to initialize the state of a component. However, in modern versions, the "constructor" method is preferred for initializing state. The "constructor" method is a standard JavaScript constructor that is called when an instance of the component is created, allowing for more flexibility in handling state initialization.

Summary & Key Takeaways

• DOM-related questions: Differentiate between virtual DOM and real DOM, explain React and its features, discuss the meaning of JSX, and describe the advantages of using virtual DOM.

• Architecture: Understand the meaning of component-based architecture and the use of higher-order components (HOCs) in React.

• Redux: Explain the components of Redux, the advantages of using Redux, and the difference between Flux and Redux.

• Components and States: Differentiate between controlled and uncontrolled components, understand the use of keys in React, and explain pure components and refs.

• Other topics: Discuss the strict mode component, avoiding the need for binding, production mode in React, and the use of conditional attributes in components.