React.js MCQs (Chapterwise Multiple Choice Questions)

What is the difference between props and state?

State is similar to props, but it is private and fully controlled by the component.

Props is similar to state, but it is private and fully controlled by the component.

State and props both are similar

None of the above

Answer & Explanation

Correct Answer: State is similar to props, but it is private and fully controlled by the component.

Note: This Question is unanswered, help us to find answer for this one

What is the children prop?

A property that adds child components to state

A property that lets you pass components as data to other components

A property that lets you set an array as a property

A property that lets you pass data to child elements

Answer & Explanation

Correct Answer: A property that lets you pass components as data to other components

Note: This Question is unanswered, help us to find answer for this one

Which of the following statements is/are correct about the React method, createFactory()?

It returns a function that is used for producing React elements of a given type.

For createFactory() method, the type argument can only be a React component type (a class or a function).

React.createFactory() can be invoked directly while using JSX.

All of the above.

Answer & Explanation

Correct Answer: It returns a function that is used for producing React elements of a given type.

Note: This Question is unanswered, help us to find answer for this one

Consider the current state as following:
{
isHidden: true,
title: 'React new Example'
}
Suppose the this.setState(nextState) method is called and the current state is updated to the following:
{
isHidden: false
}
Which of the following is the correct way in which React will merge these two states?

{

isHidden: false

}

{

isHidden: true,

title: ' '

}

{

isHidden: true,

title: 'React new Example'

}

{

isHidden: false,

title: 'React new Example'

}

Answer & Explanation

Correct Answer:

{

isHidden: false,

title: 'React new Example'

}

Note: This Question is unanswered, help us to find answer for this one

Which of the following arguments are passed to the componentWillUpdate() method that is called immediately before React updates the DOM?

nextProps

nextState

this.handleNewTweet

prevProps

Answer & Explanation

Correct Answer: nextState

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What package contains the render() function that renders a React element tree to the DOM?

React

ReactDOM

Render

DOM

Answer & Explanation

Correct Answer: ReactDOM

Note: This Question is unanswered, help us to find answer for this one

Which of the following Lifecycle methods of ReactJS Component is/are used to clear up the memory Space?

componentWillMount()

componentWillUpdate()

Both a and b

Neither a nor b

Answer & Explanation

Correct Answer: componentWillUpdate()

Note: This Question is unanswered, help us to find answer for this one

In relation to React Flux, which of the following arguments is/are passed to the connect function which is used to connect the root component to the store?

state and select function

state and action

Only action

Only select function

Answer & Explanation

Correct Answer: Only select function

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What is the testing library most often associated with React?

Mocha

Chai

Sinon

Jest

Answer & Explanation

Correct Answer: Jest

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Which of the following statements is/are correct about ReactJS?
i) It is mandatory to use JSX in React development.

ii) One-way data flow is implemented by React.

Only statement i) is correct.

Only statement ii) is correct.

Both statements i) and ii) are correct.

Neither statement i) nor ii) is correct

Answer & Explanation

Correct Answer:

Only statement ii) is correct.

Note: This Question is unanswered, help us to find answer for this one

React.js Quick Quiz

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React.js MCQ

React.js Quick Quiz

What is the difference between props and state?

What is the children prop?

Which of the following statements is/are correct about the React method, createFactory()?

Consider the current state as following:{ isHidden: true, title: 'React new Example'}Suppose the this.setState(nextState) method is called and the current state is updated to the following:{ isHidden: false}Which of the following is the correct way in which React will merge these two states?

Which of the following arguments are passed to the componentWillUpdate() method that is called immediately before React updates the DOM?

What package contains the render() function that renders a React element tree to the DOM?

Which of the following Lifecycle methods of ReactJS Component is/are used to clear up the memory Space?

In relation to React Flux, which of the following arguments is/are passed to the connect function which is used to connect the root component to the store?

What is the testing library most often associated with React?

Which of the following statements is/are correct about ReactJS?i) It is mandatory to use JSX in React development.ii) One-way data flow is implemented by React.

Consider the current state as following:
{
isHidden: true,
title: 'React new Example'
}
Suppose the this.setState(nextState) method is called and the current state is updated to the following:
{
isHidden: false
}
Which of the following is the correct way in which React will merge these two states?

Which of the following statements is/are correct about ReactJS?
i) It is mandatory to use JSX in React development.

ii) One-way data flow is implemented by React.