React Basics

1/25 React is mainly used for building ___.
- Database
- Connectivity
- User interface
- Design Platform
2/25 The lifecycle methods are mainly used for ___.
- keeping track of event history
- enhancing components
- freeing up resources
- none of the above
3/25 ___ can be done while multiple elements need to be returned from a component.
- Abstraction
- Packing
- Insulation
- Wrapping
4/25 What is used to pass data to a component from outside?
- setState
- render with arguments
- PropTypes
- props
5/25 What will happen if the following render() method executes?
```
render(){

let langs = ["Ruby","ES6","Scala"]

return (<div>

{langs.map(it => <p>{it}</p>)}

</div>)

}
```
- Displays the list of languages in the array
- Error. Cannot use direct JavaScript code in JSX
- Displays nothing
- Error. Should be replaced with a for..loop for correct output
6/25 What advantages does ReactJS have?
- Increases the application’s performance with Virtual DOM
- JSX makes a code that is easy to read and write
- It renders both on client and server side
- Easy to integrate with other frameworks(Angular, BackboneJS) since it is only a view library
- All of the above
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 React merges the object provided into the current state using ___.
- setState()
- State()
9/25 The arbitrary inputs of components are called ___.
- Keys
- Props
- Elements
- Ref
10/25 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
11/25 What is a higher-order component in React?
- A component that renders other components
- A component with higher z-index
- A stateful component
- A component with higher-order functions
12/25 Which is a correct way to create a state in a class component?
```
class MyComponent extends React.Component { ... }
```
- this.state = { value: '' };
- const state = { value: '' };
- useState({ value: '' });
- setState({ value: '' });
13/25 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
14/25 How do you pass a prop named 'data' to a component named 'MyComponent'?
- <MyComponent data={this.props.data} />
- <MyComponent props={data} />
- <MyComponent>{data}</MyComponent>
- <MyComponent data='data' />
15/25 What is the use of 'useState' hook in React?
- To manage state in functional components
- To link state between components
- To update state in class components
- To store data in the browser's local storage
16/25 What does 'props.children' represent in a React component?
- The state of the parent component
- The children passed to the component
- A type of React child component
- The props of the child components
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 What is the purpose of the 'useEffect' hook?
- To handle state changes
- To create a new component
- To perform side effects in functional components
- To connect to a Redux store
19/25 What is 'prop drilling' in React?
- Passing props through multiple layers of components
- A method to define PropTypes in a component
- Drilling down to find errors in props
- A React library for handling properties
20/25 What is the purpose of the 'key' prop in React lists?
- To enhance performance
- To uniquely identify each element
- For styling
- To enable React's virtual DOM
21/25 How do you share state between two components that are not parent-child in React?
- Using global variables
- Using the Context API
- Passing props through intermediate components
- Using a state management library like Redux
22/25 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
23/25 How do you handle form submissions in React?
- Using an onSubmit event handler
- With a dedicated form management library
- By directly submitting to the server
- React does not support form submissions
24/25 Which is a valid way to create a component in React?
- function MyComponent() { return <div/>; }
- new ReactComponent(MyComponent)
- React.createComponent(MyComponent)
- class MyComponent extends ReactElement { ... }
25/25 What is the use of the 'useEffect' hook in React?
- To manage component state
- To perform side effects in functional components
- For rendering optimizations
- To create reusable components
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React Basics

1/25 React is mainly used for building ___.

2/25 The lifecycle methods are mainly used for ___.

3/25 ___ can be done while multiple elements need to be returned from a component.

4/25 What is used to pass data to a component from outside?

5/25 What will happen if the following render() method executes?

6/25 What advantages does ReactJS have?

7/25 What disadvantages does ReactJS have?

8/25 React merges the object provided into the current state using ___.

9/25 The arbitrary inputs of components are called ___.

10/25 What is the use of the 'useReducer' hook in React?

11/25 What is a higher-order component in React?

12/25 Which is a correct way to create a state in a class component?

13/25 What does the 'useMemo' hook do in React?

14/25 How do you pass a prop named 'data' to a component named 'MyComponent'?

15/25 What is the use of 'useState' hook in React?

16/25 What does 'props.children' represent in a React component?

17/25 What does 'React.Fragment' do?

18/25 What is the purpose of the 'useEffect' hook?

19/25 What is 'prop drilling' in React?

20/25 What is the purpose of the 'key' prop in React lists?

21/25 How do you share state between two components that are not parent-child in React?

22/25 What is the purpose of 'useReducer' in React?

23/25 How do you handle form submissions in React?

24/25 Which is a valid way to create a component in React?

25/25 What is the use of the 'useEffect' hook in React?