Fever Hospital consultant pulmonologist Interview Questions and Answers

React is a JavaScript library for building user interfaces.

• React allows developers to create reusable UI components.

• It uses a virtual DOM to efficiently update the UI.

• React can be used with other libraries and frameworks.

• It was developed by Facebook and is widely used in web development.

• Examples of companies using React include Netflix, Airbnb, and Instagram.

Virtual DOM is a lightweight copy of the actual DOM used for efficient updates in web applications.

• Virtual DOM is a concept used in ReactJS and other modern web frameworks.

• It allows for efficient updates by only updating the parts of the actual DOM that have changed.

• Virtual DOM is a tree-like structure that represents the actual DOM.

• Changes made to the virtual DOM are compared to the previous version to determine what ...read more

React has three lifecycle methods: Mounting, Updating, and Unmounting.

• Mounting: When a component is being inserted into the DOM. componentDidMount() is an example.

• Updating: When a component is being re-rendered. componentDidUpdate() is an example.

• Unmounting: When a component is being removed from the DOM. componentWillUnmount() is an example.

• I have implemented these methods in various projects, such as using componentD...read more

React hooks are a way to use state and other React features in functional components.

• Hooks were introduced in React 16.8.

• useState is a hook that allows functional components to have state.

• useEffect is a hook that allows functional components to have side effects.

• useContext is a hook that allows functional components to consume context.

• Hooks can only be used in functional components, not in class components.

• Example: con...read more

Redux is a state management library for JavaScript applications. Middleware is a function that sits between the action and reducer. Redux components are React components that are connected to the Redux store.

• Redux is used to manage the state of an application in a predictable way.

• Middleware is used to intercept and modify actions before they reach the reducer.

• Redux components are React components that are connected to ...read more

Error boundary is a React component that catches JavaScript errors during rendering.

• It is used to handle errors that occur during rendering in React applications.

• It helps to prevent the entire application from crashing due to a single error.

• It is implemented using the componentDidCatch lifecycle method.

• It can be used to display a fallback UI or log the error for debugging purposes.

Node is a JavaScript runtime built on Chrome's V8 JavaScript engine.

• Node allows developers to run JavaScript on the server-side.

• It has a non-blocking I/O model that makes it efficient for handling large amounts of data.

• Node has a package manager called npm that makes it easy to install and manage third-party libraries.

• Some popular frameworks built on Node include Express, NestJS, and Meteor.

Node is single threaded for simplicity and consistency. Multi-threading can be achieved through child processes or worker threads.

• Node's single thread model simplifies programming and avoids race conditions.

• Child processes can be used to run multiple instances of Node, each with its own thread.

• Worker threads can be used to create additional threads within a single Node process.

• Multi-threading can improve performance fo...read more