React and JavaScript Quiz

What does useEffect() do in React?

• Fetches data from an API

• Handles lifecycle events like componentDidMount

• Renders components

• Creates a new state

Which of the following is a higher-order component (HOC)?

• useState

• withAuth(Component)

• useEffect

• ComponentDidMount

Which keyword is used to create a constant in ES6?

• var

• constant

• const

• static

What is the primary use of the Redux Toolkit?

• CSS styling

• Simplifying Redux state management

• Creating custom hooks

• Building class-based components

Which of the following is NOT true about pure functions?

• They always return the same output for the same input

• They do not cause side effects

• They can modify global variables

• They are easy to test

What does axios.post() return?

• A response object

• An object with a data property only

• A pending fetch call

• A Promise

What’s the purpose of render() in class-based React components?

• Run side effects

• Return JSX

• Update state

• Destroy component

Which operator is used for optional chaining in JavaScript?

• &&

• ?.

• !

• ??

What does componentDidMount() do in a React class component?

• Triggers before the component renders

• Triggers after the component unmounts

• Triggers immediately after the component is mounted

• Triggers before render()

Which hook is used to manage form input state?

• useRef()

• useForm()

• useEffect()

• useState()