Loading... Login Loading... Register

React State Management Quiz

Want to learn more than this quiz offers you? Have a look at my Frontend web development courses.

Create an account and save your quiz results

Login and save your results

First Name *

Last Name *

Email *

Password *

Confirm Password *

I agree to the Terms of Service & Privacy Policy.

Add me to your newsletter.

Question 1/15

What is React's useEffect hook used for?

Select your answer

To perform side effects in function components.

To directly update the DOM manually.

To optimize component rendering performance.

To initialize state in class components.

Question 2/15

When is it recommended to use useCallback in React?

Select your answer

When you want to dispatch actions within Redux reducers.

When you render a list of elements with dynamic keys.

When you need to attach a ref to a DOM element.

When you want to memoize a function to prevent unnecessary re-creation.

Question 3/15

What is the primary purpose of React's useState hook?

const [count, setCount] = useState(0);

Select your answer

To fetch data from a remote server

To navigate between routes in a React application

To manage component state within functional components

To handle form submissions in react

Question 4/15

What is the difference between useState and useReducer hooks in React?

Select your answer

useState manages global state, while useReducer is local only.

useState manages asynchronous state changes, while useReducer deals with synchronous changes.

useState is used for local component state, while useReducer is used for complex state logic with dispatch actions.

useState can only be used in class components, useReducer is for functional components.

Question 5/15

When handling forms in React, why is controlled component considered best practice?

Select your answer

Asynchronous JavaScript functions can execute during creation.

CSS styles are automatically applied to form elements.

Because it synchronizes the input data with the component's state.

It uses HTML validation for form inputs.

Question 6/15

What mechanism does Redux use to update its state?

Select your answer

Reducers compute a new state based on actions dispatched.

Action creators update the global state through context managers.

The state is serialized and written into session storage upon updates.

Components directly mutate the store object.

Question 7/15

Consider the following use of useEffect. When does the effect run?

useEffect(() => { console.log('Updated!'); }, [count]);

Select your answer

Every time the component re-renders.

Whenever the 'count' state changes.

Never, because 'useEffect' is not properly configured.

Only once, when the component mounts.

Question 8/15

Why is the concept of immutable state vital in Redux?

Select your answer

The mutable state causes React to throw errors.

It allows CSS to adjust automatically with state changes.

It integrates directly into Vue.js applications.

It ensures predictability and verifiability of application state.

Question 9/15

What is the common way to improve performance for a component consistently re-rendering due to state changes?

Select your answer

Limit the number of state variables

Publish the component in a separate thread

Use

React.memo

to wrap the component

Increase the delay between re-renders

Question 10/15

In React, what is the main benefit of lifting state up?

Select your answer

To enable JSX to be converted to strings.

To reduce execution context in large applications.

To enable two sibling components to share and sync state.

To add more states directly to child components.

Question 11/15

What does the dispatch function of useReducer hook return?

Select your answer

A function that allows you to send actions to the reducer.

A new state object directly after handling an action.

A subscribe function to listen to state changes.

The current state and a function to update that state.

Question 12/15

What is the default behavior of Context in React regarding re-renders?

Select your answer

The components using Context never re-render.

It causes re-renders whenever the Provider's value changes.

It only re-renders the component where the Context is defined.

It causes re-renders depending on the content of the values, not structural change.

Question 13/15

What problem does React Context API primarily solve?

Select your answer

Passing data through a simple component tree without prop drilling

Global style management

Reducing state updates from asynchronous actions

Routing between components

Question 14/15

What problem does memoization solve in the context of React?

Select your answer

Aligning style sheets across components.

Reusing the last computed value to avoid costly re-computations.

Replacing server-side rendering with client-side execution.

Synchronizing local component time with server time.

Question 15/15

In a React functional component, what is the correct way to update a state variable that holds an object?

const [user, setUser] = useState({ name: 'John', age: 30 });

Select your answer

user.name = 'Jane'; setUser(user);

setUser(user => user.name = 'Jane');

setUser({ ...user, name: 'Jane' });

setUser({ name: 'Jane', age: 32 });

Your Results

You did not answer any questions correctly.

Your Answers

Question 1/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is React's useEffect hook used for?

Available answers

To perform side effects in function components.

To directly update the DOM manually.

To optimize component rendering performance.

To initialize state in class components.

The useEffect hook in React is used for performing side effects in function components, such as data fetching, subscriptions, or manually changing the DOM. It replaces the side-effect features of lifecycle methods in class components.

Question 2/15

😊 Your answer was correct 🙁 Your answer was incorrect

When is it recommended to use useCallback in React?

Available answers

When you want to dispatch actions within Redux reducers.

When you render a list of elements with dynamic keys.

When you need to attach a ref to a DOM element.

When you want to memoize a function to prevent unnecessary re-creation.

The useCallback hook in React is recommended when you have a function that needs to retain the same instance between renders, preventing unnecessary re-creations especially when passing it as a prop to child components that could result in unneeded renders.

Question 3/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the primary purpose of React's useState hook?

const [count, setCount] = useState(0);

Available answers

To fetch data from a remote server

To navigate between routes in a React application

To manage component state within functional components

To handle form submissions in react

The useState hook in React allows you to add state to functional components. It returns an array with the state value and a function to update it. The code snippet

const [count, setCount] = useState(0);

initializes a state variable count with a value of 0.

Question 4/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the difference between useState and useReducer hooks in React?

Available answers

useState manages global state, while useReducer is local only.

useState manages asynchronous state changes, while useReducer deals with synchronous changes.

useState is used for local component state, while useReducer is used for complex state logic with dispatch actions.

useState can only be used in class components, useReducer is for functional components.

The useState hook is generally used for local state management within a component. useReducer is a more powerful hook that is used when you have complex state logic involving multiple sub-values, especially when the next state depends on the previous one. It is based on Redux's principle of reducers, using a dispatch method to handle actions.

Question 5/15

😊 Your answer was correct 🙁 Your answer was incorrect

When handling forms in React, why is controlled component considered best practice?

Available answers

Asynchronous JavaScript functions can execute during creation.

CSS styles are automatically applied to form elements.

Because it synchronizes the input data with the component's state.

It uses HTML validation for form inputs.

Controlled components in React refer to form elements being controlled by React state. This approach ensures that the rendered form is always in sync with the component's state, providing better control over data submission, validation, and component behavior.

Question 6/15

😊 Your answer was correct 🙁 Your answer was incorrect

What mechanism does Redux use to update its state?

Available answers

Reducers compute a new state based on actions dispatched.

Action creators update the global state through context managers.

The state is serialized and written into session storage upon updates.

Components directly mutate the store object.

Redux alters its global state using reducers, which are pure functions. Upon receiving an action dispatched by action creators, these reducers compute and return a new state based on the previous state and the action.

Question 7/15

😊 Your answer was correct 🙁 Your answer was incorrect

Consider the following use of useEffect. When does the effect run?

useEffect(() => { console.log('Updated!'); }, [count]);

Available answers

Every time the component re-renders.

Whenever the 'count' state changes.

Never, because 'useEffect' is not properly configured.

Only once, when the component mounts.

The useEffect hook takes a dependency array as its second argument. In this case,

[count]

means the effect will run every time the count state changes.

Question 8/15

😊 Your answer was correct 🙁 Your answer was incorrect

Why is the concept of immutable state vital in Redux?

Available answers

The mutable state causes React to throw errors.

It allows CSS to adjust automatically with state changes.

It integrates directly into Vue.js applications.

It ensures predictability and verifiability of application state.

Maintaining an immutable state in Redux ensures predictability and verifiability. Each state change creates a new copy of the state, ensuring that changes are explicit and the application state remains predictable, which simplifies debugging.

Question 9/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the common way to improve performance for a component consistently re-rendering due to state changes?

Available answers

Limit the number of state variables

Publish the component in a separate thread

Use <pre><code>React.memo</code></pre> to wrap the component

Increase the delay between re-renders

To prevent unnecessary re-renders due to the same props and state in a React component, wrapping the component with React.memo optimizes performance by memoizing the rendered output unless there are meaningful prop changes.

Question 10/15

😊 Your answer was correct 🙁 Your answer was incorrect

In React, what is the main benefit of lifting state up?

Available answers

To enable JSX to be converted to strings.

To reduce execution context in large applications.

To enable two sibling components to share and sync state.

To add more states directly to child components.

Lifting state up in React involves moving shared state to a common ancestor component, allowing different sibling components to access and sync the state. This approach supports better data flow and state management across components.

Question 11/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does the dispatch function of useReducer hook return?

Available answers

A function that allows you to send actions to the reducer.

A new state object directly after handling an action.

A subscribe function to listen to state changes.

The current state and a function to update that state.

When you use the useReducer hook, it returns two values: the current state and a dispatch function. The dispatch function is used to send actions to the reducer function to update the state according to the logic defined in the reducer.

Question 12/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the default behavior of Context in React regarding re-renders?

Available answers

The components using Context never re-render.

It causes re-renders whenever the Provider's value changes.

It only re-renders the component where the Context is defined.

It causes re-renders depending on the content of the values, not structural change.

React's Context API will cause components that are consuming context data to re-render whenever there is a change in the context's Provider value. This default behavior can be optimized using React.memo or memoized selectors when appropriate.

Question 13/15

😊 Your answer was correct 🙁 Your answer was incorrect

What problem does React Context API primarily solve?

Available answers

Passing data through a simple component tree without prop drilling

Global style management

Reducing state updates from asynchronous actions

Routing between components

The React Context API allows you to share values between components without having to explicitly pass props through every level of the tree. This is particularly useful to avoid 'prop drilling' when you have deeply nested components.

Question 14/15

😊 Your answer was correct 🙁 Your answer was incorrect

What problem does memoization solve in the context of React?

Available answers

Aligning style sheets across components.

Reusing the last computed value to avoid costly re-computations.

Replacing server-side rendering with client-side execution.

Synchronizing local component time with server time.

Memoization in React prevents unnecessary recalculations of expensive computations by reusing the previously computed value, provided the input dependencies haven't changed. This enhances performance by avoiding repeated computations.

Question 15/15

😊 Your answer was correct 🙁 Your answer was incorrect

In a React functional component, what is the correct way to update a state variable that holds an object?

const [user, setUser] = useState({ name: 'John', age: 30 });

Available answers

<pre><code>user.name = 'Jane'; setUser(user);</code></pre>

<pre><code>setUser(user => user.name = 'Jane');</code></pre>

<pre><code>setUser({ ...user, name: 'Jane' });</code></pre>

<pre><code>setUser({ name: 'Jane', age: 32 });</code></pre>

When updating a state variable that holds an object in React, you should use the spread operator to create a new object with the updated fields. The option

setUser({ ...user, name: 'Jane' });

creates a new object with the existing properties from user and only changes the name property.