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React Basics

1/25 The lifecycle methods are mainly used for ___.
- keeping track of event history
- enhancing components
- freeing up resources
- none of the above
2/25 Which of the following methods in a React Component should be overridden to stop the component from updating?
- willComponentUpdate
- shouldComponentUpdate
- componentDidUpdate
- componentDidMount
3/25 Which of the following methods in a React Component is called after the component is rendered for the first time?
- componentDidUpdate
- componentDidMount
- componentMounted
- componentUpdated
4/25 How do you write an inline style which specifies the font-size:12px and color:red; in JSX?
- style={{font-size:12,color:'red'}}
- style={{fontSize:'12px',color:'red'}}
- style={fontSize:'12px',color:'red'}
- style={{font-size:12px,color:'red'}}
5/25 What is state in React?
- A persistant storage.
- An internal data store (object) of a component.
6/25 What is ReactJS?
- Server side Framework
- User-interface framework
- Library for building interaction interfaces
7/25 What disadvantages does ReactJS have?
- It is only a view layer. You have to plug your code for Ajax requests, events and so on.
- The library is pretty large.
- The learning curve can be slow.
- All of the above options
8/25 In React, which method is used to create a context?
- React.createContext()
- React.createState()
- React.createComponent()
- React.createRef()
9/25 What is the use of the 'useReducer' hook in React?
- To manage state in a component
- To reduce the size of a component
- For state management with a reducer function
- To enhance performance
10/25 What is the purpose of the 'key' prop in a React list?
- To identify each element uniquely
- For styling elements
- To enhance performance
- To trigger events
11/25 What does 'PureComponent' do in React?
- Manages pure functions
- Prevents re-rendering if props and state have not changed
- Cleans up the component
- Enhances component performance
12/25 What is the default port where a create-react-app project runs?
- 3000
- 8080
- 5000
- 8000
13/25 In React, what does the 'useEffect' hook do?
- Manages component lifecycle
- Handles state changes
- Creates a new effect
- None of the above
14/25 Which method is necessary to define in a class component in React?
- componentDidMount()
- shouldComponentUpdate()
- render()
- getDerivedStateFromProps()
15/25 What does the 'useMemo' hook do in React?
- It memorizes a computed value
- It saves memory usage
- It recalls previously rendered components
- It memorizes the component state
16/25 How do you conditionally render components in React?
- Using if-else statements inside JSX
- Using the ternary operator inside JSX
- Using for loop inside JSX
- Using switch-case inside JSX
17/25 What does 'React.Fragment' do?
- It groups a list of children without adding extra nodes to the DOM
- It is a method to optimize performance
- It is used to fragment a component into smaller components
- It is a way to render components asynchronously
18/25 How does React handle form submission?
- Using an event handler on the form element
- By automatically sending a POST request
- Using a dedicated React form submission library
- React cannot handle form submissions
19/25 In which scenario would you use React's 'useRef' hook?
- To directly interact with a DOM element
- To update the component's state
- To fetch data from an API
- To create a new React component
20/25 What does 'lifting state up' mean in React?
- Moving state to a common ancestor of components that need it
- Increasing the performance of the state updates
- Automatically handling state changes in child components
- Transferring state to a higher-order component
21/25 Which method is the right choice to fetch data in a useEffect hook?
- componentDidMount
- useFetch
- fetch API
- getData()
- useDataFetching
22/25 How can you prevent a function from being called too frequently in React, such as during window resizing?
- Using shouldComponentUpdate
- Using PureComponent
- Using debounce or throttle techniques
- Using useEffect with an empty dependency array
23/25 What does 'prop drilling' refer to in React?
- Passing props to deep child components
- Setting default prop values
- Validating prop types
- Updating props from child components
24/25 In React, what is a 'higher-order component' (HOC)?
- A component with higher z-index
- A component that returns another component
- A stateful component
- A component that renders HTML elements
25/25 What is the purpose of 'useReducer' in React?
- To handle component lifecycle
- For state management using a reducer function
- To reduce the bundle size of a React app
- To optimize rendering performance
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