React.js Quiz | Set-1

Question 1

Which of the following command is used to create react-js-app ?

• A. npx create-react-app appname
• B. npm install create-react-app
• C. npx install create-react-app -g
• D. install - l create-react-app

Answer: (A)

The correct syntax for installing react app is npx create-react-app app name where app name is the name of the app you want to create.

Question 2

In React.js which one of the following is used to create a class for Inheritance ?

• A. Create
• B. Extends
• C. Inherits
• D. Delete

Answer: (B)

The meaning of Extends in react.js is to create a class for the Inheritance So the correct answer is Extend.

Question 3

What is the default port number in which the application run ?

• A. 3000
• B. 8080
• C. 5000
• D. 3030

Answer: (A)

The default port number in which react application runs are 3000.

Question 4

Which of the following valid component return type of React ?

• A. 2
• B. 5
• C. 1
• D. 3

Answer: (C)

The only valid component return type of React. The return type in React is by render() function.

Question 5

Which of the following is a way to handle data in React.js ?

• A. State & Props
• B. Services & Components
• C. State & Services
• D. State & Component

Answer: (A)

State and Props are ways to handle data in React.js where the state is mutable and props are unchangeable.

Question 6

Which of the following is must for the API in React.js ?

• A. SetinitialComponent
• B. renderComponent
• C. render
• D. All of the above

Answer: (B)

The renderComponent is not a function that is used as API for the React.js.

Question 7

Which of the following is true regarding Babel ?

• A. Compiler
• B. Transpilar
• C. Both of the above
• D. None of the above

Answer: (C)

Babel is both compiler and Transpiler which is used to run the react.js application.

Question 8

In React.js, how we can pass the data from one component to another in React.js ?

• A. SetState
• B. Render with arguments
• C. Props
• D. PropTypes

Answer: (C)

Props can help to pass the data from one component from another in react.js. Props are un-mutable so that they cant be changed.

Question 9

Which of the following function is true about changing the state in React.js ?

• A. this.State{}
• B. this.setState
• C. this.setChangeState
• D. All of the above

Answer: (B)

The this.setState is used for changing the state in React.js whenever the state changes in react then it re-render the component in the browser.

Question 10

Which of the following method is true about referring parent class in React.js ?

• A. self()
• B. inherits()
• C. this()
• D. super()

Answer: (D)

The super() is a method in which referring the parent class in react.js. It is the way for calling the constructor in React.js.