Intro - ReactJS Question & Answers

Part 1
Q1. What is React?
Q2. What are the major features of React?
Q3. What is JSX?
Q4. What is the difference between Element and Component?
Q5. How to create components in React?

Part 2
Q1. When to use a Class Component over a Function Component?
Q2. What are Pure Components?
Q3. What is state in React?
Q4. What are props in React?
Q5. What is the difference between state and props?

Part 3
Q1. What is the purpose of callback function as an argument of setState()?
Q2. What is the difference between HTML and React event handling?
Q3. What are synthetic events in React?
Q4. What is inline conditional expressions?
Q5. What are "key" props and what is the benefit of using them in arrays of elements?

Part 4
Q1. What is the use of refs?
Q2. What are forward refs?
Q3. What is Virtual DOM?
Q4. How Virtual DOM works?
Q5. What is the difference between Shadow DOM and Virtual DOM?

Part 5
Q1. What is React Fiber?
Q2. What is the main goal of React Fiber?
Q3. What are controlled components?
Q4. What are uncontrolled components?
Q5. What is the difference between createElement and cloneElement?

Part 6
Q1. What is Lifting State Up in React?
Q2. What are the lifecycle methods of React?
Q3. What are Higher-Order Components?
Q4. What is "context"?
Q5. What is "children" prop?

Part 7
Q1. What is reconciliation?
Q2. Why is it necessary to "capitalize" component names?
Q3. Why React uses className over class attribute?
Q4. What are fragments?
Q5. Why fragments are better than container divs?

Part 8
Q1. What are stateless components?
Q2. What are stateful components?
Q3. What are the advantages of React?
Q4. What are the limitations of React?
Q5. What are error boundaries in React v16?

Part 9
Q1. How error boundaries handled in React v15?
Q2. What are the recommended ways for static type checking?
Q3. What is the use of react-dom package?
Q4. What is the purpose of render method of react-dom?
Q5. What is ReactDOMServer?

Part 10
Q1. How events are different in React?
Q2. What will happen if you use the setState method in the constructor?
Q3. Is it good to use the setState method in the componentWillMount method?
Q4. Why do we need to be careful when spreading props on DOM elements?
Q5. How you use decorators in React?

Part 11
Q1. How to enable production mode in React?
Q2. What is CRA and its benefits?
Q3. What is the lifecycle methods order in mounting?
Q4. What is the difference between createElement() and cloneElement() methods?
Q5. What is a switching component?

Part 12
Q1. Why do we need to pass a function to setState()?
Q2. What is the strict mode in React?
Q3. What are React Mixins?
Q4. Why should component names start with a capital letter?
Q5. Can you force a component to re-render without calling setState?

Part 13
Q1. What is the difference between React and ReactDOM?
Q2. Why ReactDOM is separated from React?
Q3. What is the difference between setState() and replaceState() methods?
Q4. What is the recommended approach of removing an array element in React state?
Q5. Why you can't update props in React?

Part 14
Q1. Why is a component constructor called only once?
Q2. Is it possible to use async/await in plain React?
Q3. What are render props?
Q4. What is React Router?
Q5. How React Router is different from history library?

Part 15
Q1. What is React Intl?
Q2. What are the main features of React Intl?
Q3. What is Shallow Renderer in React testing?
Q4. What is TestRenderer package in React?
Q5. What is the purpose of ReactTestUtils package?

Part 16
Q1. What is flux?
Q2. What is Redux?
Q3. What are the core principles of Redux?
Q4. What are the downsides of Redux compared to Flux?
Q5. Can I dispatch an action in reducer?

Part 17
Q1. What are the drawbacks of MVW pattern?
Q2. Are there any similarities between Redux and RxJS?
Q3. What is the difference between React context and React Redux?
Q4. Why are Redux state functions called reducers?
Q5. What is the difference between component and container in React Redux?

Part 18
Q1. What is redux-saga?
Q2. What is the mental model of redux-saga?
Q3. What is Redux Thunk?
Q4. What are the differences between redux-saga and redux-thunk?
Q5. What is Redux DevTools?

Part 19
Q1. What are the features of Redux DevTools?
Q2. What are Redux selectors?
Q3. What is Redux Form?
Q4. What are the main features of Redux Form?
Q5. What is the difference between React Native and React?

Part 20
Q1. How to test React Native apps?
Q2. How to debug your React Native?
Q3. What is reselect and how it works?
Q4. What is Flow?
Q5. What is the difference between Flow and PropTypes?