सीखें React को मास्टर: 09 सबसे आम साक्षात्कार प्रश्नों का समझ | तनय प्रताप हिंदी

React is a popular JavaScript library that is used to build interactive user interfaces for web applications. It is widely used by developers and companies around the world to create dynamic and responsive web applications. If you are preparing for a React interview, it is important to be familiar with the most common interview questions that you may encounter. In this tutorial, we will decode 09 of the most common React interview questions, as explained by Tanay Pratap in Hindi.

1. What is React and why is it used?
React is a JavaScript library that is used to build user interfaces for web applications. It was developed by Facebook and is open-source. React allows developers to create reusable components that can be easily updated and rendered to the DOM. React is popular because it provides an efficient way to update and manipulate UI components, making it easier to build dynamic and interactive web applications.

2. What are the key features of React?
React has several key features that make it a popular choice for building web applications. Some of the key features of React include:
– Virtual DOM: React uses a virtual DOM to improve performance by reducing the number of updates needed to the actual DOM.
– JSX: React uses JSX, a syntax extension that allows you to write HTML-like code in your JavaScript files.
– Components: React allows you to create reusable components that can be combined to build complex user interfaces.
– State management: React provides a way to manage the state of your application using the setState method.
– Lifecycle methods: React components have lifecycle methods that allow you to control the behavior of your components at different stages of their lifecycle.

3. What is JSX and how is it different from HTML?
JSX is a syntax extension for JavaScript that allows you to write HTML-like code in your React applications. JSX is not a separate language, but rather a way to write XML-like syntax within JavaScript. JSX makes it easier to build user interfaces in React by allowing you to write HTML-like code directly in your JavaScript files. JSX is similar to HTML, but there are some key differences, such as:
– In JSX, you can use JavaScript expressions within curly braces {}
– JSX elements are transformed into JavaScript using a compiler like Babel
– JSX elements can be nested and combined with JavaScript logic

4. What are components in React?
Components are the building blocks of React applications. A component is a reusable piece of UI that can be rendered to the DOM. Components can be simple, like a button or a form input, or complex, like a navbar or a modal. In React, components can be divided into two types: functional components and class components. Functional components are simple functions that take props as input and return JSX. Class components are JavaScript classes that extend from the React.Component class and have access to lifecycle methods and state.

5. What is state in React and how is it different from props?
State and props are two important concepts in React that are used to manage data in your components. State is used to store and update data within a component, while props are used to pass data from a parent component to a child component. State is managed internally by the component and can be updated using the setState method. Props are passed down from a parent component and are read-only within the child component. State is used to store data that can change over time, while props are used to pass data from one component to another.

6. What are lifecycle methods in React and how are they used?
Lifecycle methods are special methods that are called at different stages of a component’s lifecycle in React. There are several lifecycle methods in React, including componentDidMount, componentDidUpdate, and componentWillUnmount. These methods allow you to control the behavior of your components at different stages, such as when the component is mounted to the DOM, updated, or unmounted. Lifecycle methods are used to perform tasks like fetching data from an API, updating the state of a component, or cleaning up resources when a component is removed from the DOM.

7. What is the difference between controlled and uncontrolled components in React?
Controlled components and uncontrolled components are two ways to manage form data in React. In a controlled component, the form data is controlled by the component’s state. This means that the value of the form input is stored in the component’s state and is updated whenever the input changes. In an uncontrolled component, the form data is managed by the DOM. This means that the value of the form input is stored in the DOM and is accessed using a ref. Controlled components are preferred in React because they provide a single source of truth for the form data and make it easier to manage form validation and submission.

8. What are higher-order components (HOC) in React?
Higher-order components (HOC) are a common design pattern in React that allows you to enhance the functionality of your components by wrapping them in a higher-order component. HOCs are functions that take a component as input and return a new component with added functionality. HOCs are often used to encapsulate common behaviors like data fetching, authentication, or styling. HOCs are a powerful tool in React that allows you to create reusable and composable components that enhance the functionality of your application.

9. What are hooks in React and how are they used?
Hooks are a new feature introduced in React 16.8 that allows you to use state and other React features in functional components. Hooks are a way to add stateful logic to functional components without using class components. There are several built-in hooks available in React, such as useState, useEffect, and useContext. Hooks allow you to manage state, perform side effects, and access context in functional components. Hooks are a powerful addition to React that makes it easier to write and organize code in functional components.

In conclusion, React is a powerful library that is widely used to build dynamic and interactive user interfaces for web applications. By familiarizing yourself with the most common React interview questions and concepts, you can improve your chances of success in a React interview. Mastering React requires a solid understanding of key concepts like components, state, props, lifecycle methods, and hooks. By practicing these concepts and building projects with React, you can become proficient in React and excel in React interviews. Happy coding!