Q1. What is React JS?
React JS is a JavaScript library used for building user interfaces, particularly single-page applications. Developed by Facebook, it allows developers to create reusable UI components.
Q2. What are the key features of React JS?
React JS offers features like virtual DOM for efficient rendering, component-based architecture for reusability, JSX syntax for easy templating, and one-way data binding for predictable state management.
Q3. What is JSX in React?
JSX (JavaScript XML) is a syntax extension used in React for describing the UI components. It allows developers to write HTML-like code within JavaScript, making it easier to visualize and understand the structure of UI components.
Q4. What is a component in React?
In React, a component is a self-contained module that encapsulates a piece of UI. Components can be reusable and can represent any part of a user interface, from simple buttons to complex forms.
Q5. What is a state in React?
State in React is an object that represents the current data of a component. It can be modified over time in response to user actions or other events, triggering UI updates. State management is essential for building interactive and dynamic user interfaces.
Q6. What is props in React?
Props (short for properties) are a way to pass data from parent components to child components in React. They are read-only and are used to customize the behavior and appearance of child components based on the parent’s data.
Q7. What is the difference between state and props in React?
State is managed internally by a component and can be modified over time, while props are passed from parent components and are immutable within the child component. State is used for internal component data, while props are used for inter-component communication.
Q8. What are the lifecycle methods in React?
React components have lifecycle methods that allow developers to hook into different stages of a component’s lifecycle, such as mounting, updating, and unmounting. Examples include componentDidMount, componentDidUpdate, and componentWillUnmount.
Q9. What is the significance of keys in React lists?
Keys are special attributes used by React to identify and track elements in lists. They help React efficiently update the UI by providing a stable identity to each list item, enabling better performance and avoiding unnecessary re-renders.
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