Mastering React: Decoding 09 Most Common Interview Questions | Tanay Pratap Hindi

Summary

This video script provides a comprehensive guide to key theoretical concepts that are essential for a React interview. It covers React's unique features like the virtual DOM, unidirectional data flow, and component-based architecture. It explains important topics such as state vs props, server-side vs client-side rendering, and React Fiber. The script also highlights advanced concepts like refs, synthetic events, and hooks, as well as their role in optimizing React applications. The information is valuable for preparing for React-related job interviews, offering both beginner and advanced insights into React's core principles.

Takeaways

• 😀 React is a **library**, not a framework, focused on building UI through reusable components.
• 😀 React uses a **Virtual DOM** to improve performance by updating only the necessary parts of the real DOM.
• 😀 **Unidirectional data flow** is a key feature of React, where data flows from parent to child components.
• 😀 React promotes a **component-based architecture**, allowing developers to create reusable UI components.
• 😀 **Reconciliation** in React is the process of comparing changes between the Virtual DOM and real DOM and updating only the minimal differences.
• 😀 **Props** are read-only and passed from parent to child components. Changes in props trigger re-rendering of child components.
• 😀 **State** is used to manage internal data in a component. When state changes, the component re-renders.
• 😀 React supports both **Server-Side Rendering (SSR)** and **Client-Side Rendering (CSR)**, with SSR being ideal for content-heavy or SEO-sensitive applications.
• 😀 **React Fiber** optimizes rendering by breaking the work into units (fibers) and processing updates in chunks to improve responsiveness and avoid UI blocking.
• 😀 **Refs** in React allow direct access to DOM elements or components, useful for cases like focusing or animations where React's declarative approach doesn't suffice.
• 😀 React uses **synthetic events** to provide a consistent event handling system across all browsers, avoiding compatibility issues.

Q & A

What is React and how is it different from other JavaScript frameworks?

React is a library, not a framework. Unlike traditional frameworks, React offers flexibility by allowing you to choose your own stack. React focuses on a component-based architecture and uses a virtual DOM to optimize performance. It also follows a unidirectional data flow, where data moves from parent to child components, and it is highly reusable, which sets it apart from other frameworks.

What is the Virtual DOM in React?

The Virtual DOM is a lightweight copy of the actual DOM (Document Object Model). React uses the Virtual DOM to make changes to the UI more efficiently by first updating the virtual DOM and then determining the minimal changes needed to update the real DOM, enhancing performance by reducing unnecessary DOM manipulation.

What is the concept of reconciliation in React?

Reconciliation in React refers to the process of comparing the Virtual DOM with the real DOM to identify differences (diffing algorithm). It ensures that only the necessary changes are made to the real DOM, improving performance and user experience by avoiding full re-renders of the entire DOM.

What is the difference between props and state in React?

Props (short for properties) are immutable and are passed from parent to child components. They are used to render dynamic data. State, on the other hand, is mutable and local to a component. It is used to manage the internal data of a component and can be updated based on user interaction or other events.

What is server-side rendering (SSR) in React?

Server-side rendering refers to the process of rendering a React application's HTML on the server rather than the client. This can improve the initial loading time of the app and enhance SEO since search engines can index the fully rendered HTML page directly.

What is client-side rendering (CSR) in React?

Client-side rendering involves rendering the HTML on the browser. In React, CSR occurs when the JavaScript bundle is loaded into the client browser, which then renders the app. This is useful for single-page applications (SPAs) and when the content is highly personalized or interactive.

What are refs in React?

Refs in React are used to directly access and interact with DOM elements or React components. They are helpful in scenarios like managing focus, text selection, or triggering imperative animations. However, they are usually avoided unless necessary as they break the declarative nature of React.

What is React Fiber?

React Fiber is a complete rewrite of React's core algorithm introduced in React 16. It improves the rendering process by breaking it down into smaller units of work, which helps to manage large, complex applications without blocking the UI thread. This results in more responsive user interfaces and better handling of user interactions.

What are synthetic events in React?

Synthetic events in React are a cross-browser wrapper around the native browser events. They provide a consistent API across all browsers. React handles event delegation internally, so you don’t have to worry about different implementations of events in various browsers.

What is the advantage of using hooks in React?

Hooks in React allow you to use state and other React features in functional components, making the code more reusable, testable, and cleaner. With hooks, there is no need for class-based components, simplifying the mental model of React and allowing developers to manage side effects, context, and state more efficiently.