React with TypeScript

Here’s a guide to React with TypeScript: combine React’s power with TypeScript’s type safety for robust and scalable applications.

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Question 1

What is the purpose of PropTypes in React?

  • To style components

  • To provide runtime type checking for props

  • To optimize component rendering

  • To initialize state

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Question 2

What will happen if a component receives an invalid prop type when using PropTypes?

  • The app will crash

  • A warning will be logged in the browser console

  • The component will ignore the prop

  • The app will ignore the component

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Question 3

Which of the following is the correct way to integrate TypeScript with React?

  • Use ReactTypeScript library

  • Install react-scripts-ts

  • Use tsx extension for files and define types for props and state

  • TypeScript does not support React integration

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Question 4

In a TypeScript React component, how would you type the state in a class component?

  • state: T

  • this.state: T

  • state: ReactState<T>

  • state: T extends React.Component

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Question 5

How would you define a React component's props using TypeScript?

  • interface MyComponentProps {}

  • type MyComponentProps = {}

  • Both A and B are correct

  • React.componentProps = {}

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Question 6

Given the following code, which TypeScript type should be assigned to props?

JavaScript 
interface MyComponentProps {
  name: string;
}

const MyComponent: React.FC<MyComponentProps> = (props) => {
  return <div>{props.name}</div>;
};

  • { name: string }

  • string

  • React.Props

  • any

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Question 7

You are building a TypeScript React component that accepts a count prop (number). How would you type this prop?

JavaScript 
const Counter = (props) => {
    return <div>{props.count}</div>;
};

  • Counter.propTypes = { count: PropTypes.number };

  • const Counter: React.FC<{ count: number }> = (props) => {}

  • const Counter = (props: { count: string }) => {}

  • ReactComponent<{ count: number }>

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Question 8

What is the default behavior of PropTypes if no isRequired is applied?

  • The prop is optional and won't throw a warning if not provided

  • The prop is required and throws an error

  • The prop is automatically assigned a default value

  • The app will crash if the prop is not provided

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Question 9

Which of the following is the correct way to declare prop types in a functional React component?

  • Component.propTypes = {}

  • PropTypes.Component = {}

  • this.propTypes = {}

  • componentTypes = {}

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There are 9 questions to complete.

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