React JS Crash Course with Interview Question & Answers in Telugu

Summary

This video covers essential React concepts including functional components, hooks like useState, useEffect, useCallback, useMemo, and useReducer, and key topics like synthetic events, API integration, CSS frameworks, and routing. It explains performance optimization through memorization techniques, how React's synthetic event system works, and how to manage complex state logic using useReducer. The video also introduces tools like React Router for dynamic routing and highlights libraries for testing React applications. Finally, it encourages research into advanced topics like Strict Mode and Higher Order Components for further learning.

Takeaways

• 😀 useCallback hook helps optimize performance by memorizing functions, avoiding unnecessary re-renders unless dependencies change.
• 😀 useMemo hook memorizes the result of computationally expensive functions, returning the stored result when the same arguments are passed again.
• 😀 useReducer hook is an alternative to useState, allowing for more complex state management and updating multiple states simultaneously.
• 😀 Synthetic events in React provide a cross-browser consistent event system, making event handling reliable across different browsers.
• 😀 To integrate APIs in React, you can use the Fetch API or Axios to make HTTP requests to API endpoints and handle the data in your components.
• 😀 React Router enables dynamic routing, allowing navigation between different views or URLs in a React application.
• 😀 CSS frameworks like Bootstrap, Semantic UI, Material UI, and Tailwind CSS can be used to style React components and improve UI consistency.
• 😀 Testing React applications can be done using libraries like Jest, Enzyme, Jasmine, Mocha, and Chai to ensure application functionality.
• 😀 useCallback and useMemo hooks both serve performance optimization purposes but differ in how they are applied to functions and values.
• 😀 useReducer is especially useful for handling form data and other scenarios where multiple state updates are needed collectively.
• 😀 Further research on topics like Strict Mode, Higher Order Components, and Controlled Components is crucial for deepening React knowledge.

Q & A

What is the use of the `useCallback` hook in React?

The `useCallback` hook in React is used to memorize a function so that it doesn't get redefined on every render unless its dependencies change. This optimization helps to avoid unnecessary re-renders of components that rely on that function, improving the performance of the application.

How does the `useMemo` hook improve performance in React?

The `useMemo` hook optimizes performance by memorizing the result of a computationally expensive function. It prevents recalculating the result if the same inputs are passed again, thus saving computation time and reducing unnecessary re-renders.

When would you use `useReducer` instead of `useState`?

The `useReducer` hook is preferred over `useState` when managing complex state logic or multiple state variables that depend on each other. It is more suitable for scenarios like handling form inputs or managing states in large applications, where updating multiple values together is necessary.

What are synthetic events in React?

Synthetic events in React are a cross-browser wrapper around the native DOM events. React's synthetic event system ensures that events are normalized and behave consistently across different browsers, providing additional functionality like accessing `event.target` to interact with DOM elements.

How do you integrate an API in React?

To integrate an API in React, you typically use methods like `fetch` or libraries like Axios to make HTTP requests to API endpoints. These requests retrieve or send data, which is then processed and passed into React components for rendering.

What are some CSS frameworks commonly used with React?

Popular CSS frameworks used in React development include Bootstrap, Semantic UI, Material UI, and Tailwind CSS. These frameworks provide pre-designed components and styling systems to speed up development and ensure consistency in the UI.

What is routing in React and how is it implemented?

Routing in React refers to navigating between different views or components in a single-page application. It is typically handled using the React Router library, which allows you to define routes declaratively and navigate dynamically based on user interaction.

What are some tools and libraries used for testing React applications?

Some popular testing tools for React applications include Jest, Enzyme, Mocha, and Chai. These libraries help with unit tests, integration tests, and simulating user interactions to ensure the React components function as expected.

What is the purpose of React's Strict Mode?

React's Strict Mode is a development tool used to identify potential issues in an application, such as deprecated lifecycle methods or unsafe side effects. It helps developers write cleaner, more efficient code by highlighting problems early during the development process.

What are higher-order components (HOCs) in React?

Higher-order components (HOCs) in React are functions that take a component and return a new component with additional props or behavior. They are used to share common functionality across multiple components, allowing for code reuse and separation of concerns.