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Top 10 React js interview questions.
- React is a JavaScript library for building user interfaces.
- The Virtual DOM (Document Object Model) is a representation of the actual DOM in the browser. It enables React to update only the specific parts of a web page that need to change, instead of rewriting the entire page, leading to increased performance.
- React handles updates and rendering through a virtual DOM and component-based architecture. It re-renders only the components that have actually changed efficiently and quickly.
- State and props are both used to store data in a React component, but they serve different purposes and have different characteristics.
- A Higher Order Component (HOC) in React is a function that takes a component and returns a new component with additional props.
- Server-side rendering (SSR) and client-side rendering (CSR) are two different ways of rendering a React application.
- The useEffect hook in React allows developers to perform side effects such as data fetching, subscription, and setting up/cleaning up timers, in functional components.
- React handles events through its event handling system, where event handlers are passed as props to the components. Event handlers are functions that are executed when a specific event occurs.
- Best practices for performance optimization in React include using memoization, avoiding unnecessary re-renders, using lazy loading for components and images, and using the right data structures.
- React handles testing using testing frameworks such as Jest, Mocha, and Enzyme. Jest is a popular testing framework for React applications, while Mocha and Enzyme are also widely used.
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