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Become A Certified React Developer: Practice Tests 2

Become A Certified React Developer: Practice Tests 2

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What is the use of the create-react-app command in the React.js application?

Correct! Wrong!

It is used to create a new React app is the correct option. The create-react-app command in the React.js application is used to create a new React app.

What is true for the keys given to a list of elements in React?

Correct! Wrong!

Unique among the siblings only is the correct option. Keys given to the list of elements in React should be unique among the siblings only.

React was created by :

Correct! Wrong!

Jordan Walke is the correct option. React was originally created by Jordan Walke

Which of the following life-cycle events React components have at the highest level?

Correct! Wrong!

All of the them is the correct option.

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What will happen if you render an input element with disabled = {false}?

Correct! Wrong!

It will be rendered as enabled is the correct answer. If you render an input element with disabled = {false}, it will be rendered as enabled.

We can update the state in React.js by calling to setState() method. These calls are:

Correct! Wrong!

Asynchronous in nature is the correct answer. The call to setState() method in React.js is asynchronous, and multiple calls can be batched for better performance.

Which of the following statement is true for uncontrolled components in React.js?

Correct! Wrong!

The source of truth is DOM is the correct answer. For uncontrolled components in React.js, the source of truth is component DOM.

How can you set a default value for an uncontrolled form field?

Correct! Wrong!

By using the default Value property is the correct option. We can set a default value for an uncontrolled form field by using the default Value property.

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Which of the following statement is true for controlled components in React.js?

Correct! Wrong!

The source of truth is a component state is the correct option. For controlled components in React.js, the source of truth is a component state.

What does ES6 stand for?

Correct! Wrong!

ECMAScript 6 is the correct option. ES6 stands for ECMAScript 6. ECMAScript was created to standardize JavaScript. ES6 is the 6th version of ECMAScript published in 2015. It is also known as ECMAScript 2015.

Why is the usage of setState?

Correct! Wrong!

Invoke code after the setState operation is done is the correct option.

What changes would appear in the component as soon as the state of the React component is changed?

Correct! Wrong!

It will re-render the component is the correct answer. In React.js, as soon as the state is updated, the component re-renders itself.

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Which of the following function is called to render HTML to the web page in React?

Correct! Wrong!

render() is the correct option. React renders HTML to the web page by using a function called ReactDOM.render().

React is a part of Java.

Correct! Wrong!

False is the correct option. React is a part of Java Script.

Which of the following function is used to change the state of the React.js component?

Correct! Wrong!

this.setState is the correct option. The "this.setState" function is used to change the state of the React.js component.

Which of the following is used to pass data to a component from outside in React.js?

Correct! Wrong!

Props is the correct answer. Props are used to pass data to a component from outside in React.js.

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Which of the following method refers to the parent class in React.js?

Correct! Wrong!

super() is the correct answer. The super() method refers to the parent class. If you want to call the parent's constructor method and get access to the parent's properties and methods, you can achieve it by calling the super() method in the constructor.

Which of the following best defines the "key" prop?

Correct! Wrong!

"Key" prop is a way for React to identify a newly added item in a list and compare it during the "diffing" algorithm is the correct answer. It is used to identify any new item in a list when re-rendering. It improves performance and efficiency also.

In which of the following condition, the React.js Lifecycle method static getDerivedSateFromProps(props, state) is called?

Correct! Wrong!

Both of the above is the correct option. In React.js, the static getDerivedSateFromProps(props, state) is called in both cases when a component is created and when a component is updated.

Which of the following method is not a part of ReactDOM?

Correct! Wrong!

ReactDOM.destroy() is the correct answer as ReactDOM.destroy() method is not a part of ReactDOM. ReactDOM provides the developers with an API containing the methods such as render(), findDOMNode(), unmountComponentAtNode(), hydrate(), and createPortal().

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