React context in client components in NextJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a React context with a default value.

NextJS

import React from 'react';

const MyContext = React.[1]('default');

Drag options to blanks, or click blank then click option'

AcreateContext

BuseContext

CuseState

DcreateRef

Attempts:

3 left

💡 Hint

Common Mistakes

Using useContext instead of createContext

Trying to use useState to create context

The createContext function creates a new context object with a default value.

2fill in blank

medium

Complete the code to provide the context value to child components.

NextJS

import React from 'react';

const MyContext = React.createContext('default');

export default function MyProvider({ children }) {
  return (
    <MyContext.[1] value="provided">
      {children}
    </MyContext.[1]>
  );
}

Drag options to blanks, or click blank then click option'

AuseContext

BProvider

CConsumer

DcreateContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using Consumer instead of Provider to pass value

Trying to use useContext here

The Provider component supplies the context value to its children.

3fill in blank

hard

Fix the error in the code to consume the context value inside a client component.

NextJS

"use client";

import React, { [1] } from 'react';
import { MyContext } from './MyProvider';

export default function MyComponent() {
  const value = [1](MyContext);
  return <div>{value}</div>;
}

Drag options to blanks, or click blank then click option'

AuseEffect

BcreateContext

CuseState

DuseContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using createContext instead of useContext

Trying to use useState to get context

The useContext hook is used to read the current context value inside a client component.

4fill in blank

hard

Fill both blanks to create and use a context with a default number value.

NextJS

import React from 'react';

const NumberContext = React.[1](0);

export function NumberProvider({ children }) {
  return <NumberContext.[2] value={42}>{children}</NumberContext.[2]>;
}

Drag options to blanks, or click blank then click option'

AcreateContext

BuseContext

CProvider

DConsumer

Attempts:

3 left

💡 Hint

Common Mistakes

Using useContext to create context

Using Consumer instead of Provider to pass value

Use createContext to create the context and Provider to supply the value.

5fill in blank

hard

Fill all three blanks to consume a context value and display it in a client component.

NextJS

"use client";

import React, { [1] } from 'react';
import { NumberContext } from './NumberProvider';

export default function ShowNumber() {
  const number = [2](NumberContext);
  return <p>The number is: [3]</p>;
}

Drag options to blanks, or click blank then click option'

AuseContext

BuseState

Cnumber

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState instead of useContext

Trying to display 'value' instead of the variable

Use useContext to get the context value, then display the variable holding it.

Practice

1. What is the main purpose of React context in client components?

easy

A. To share data easily without passing props through every component

B. To create new HTML elements dynamically

C. To style components with CSS

D. To handle browser events like clicks and scrolls

Solution

1. Step 1: Understand React context role

   React context allows sharing data across components without manually passing props at every level.

2. Step 2: Compare with other options

   Creating HTML elements, styling, and event handling are unrelated to React context's main purpose.

3. Final Answer:

   To share data easily without passing props through every component -> Option A

4. Quick Check:

   React context = data sharing without prop drilling [OK]

Hint: Context shares data without passing props everywhere [OK]

Common Mistakes:

• Confusing context with styling or event handling
• Thinking context creates HTML elements
• Believing context is for CSS only

2. Which of the following is the correct way to access React context in a client component?

easy

A. const value = useRef(MyContext);

B. const value = useState(MyContext);

C. const value = useContext(MyContext);

D. const value = useEffect(MyContext);

Solution

1. Step 1: Identify the hook for context access

   React provides the useContext hook to access context values inside client components.

2. Step 2: Eliminate other hooks

   useState manages state, useEffect handles side effects, and useRef manages references, none access context.

3. Final Answer:

   const value = useContext(MyContext); -> Option C

4. Quick Check:

   useContext hook = context access [OK]

Hint: Use useContext to read context in components [OK]

Common Mistakes:

• Using useState or useEffect instead of useContext
• Trying to access context without a hook
• Confusing useRef with context access

3. Given this code snippet in a Next.js client component:

import { createContext, useContext } from 'react';

const ThemeContext = createContext('light');

export default function DisplayTheme() {
  const theme = useContext(ThemeContext);
  return <div>Current theme: {theme}</div>;
}

What will be displayed if DisplayTheme is rendered without a ThemeContext.Provider?

medium

A. Current theme: undefined

B. Current theme: light

C. Current theme: null

D. Error: Context provider missing

Solution

1. Step 1: Check default context value

   The context is created with default value 'light', so if no Provider wraps the component, this default is used.

2. Step 2: Understand useContext behavior without Provider

   useContext returns the default value when no Provider is found above in the tree.

3. Final Answer:

   Current theme: light -> Option B

4. Quick Check:

   Default context value used without Provider [OK]

Hint: Default context value shows if no Provider wraps component [OK]

Common Mistakes:

• Expecting undefined or null instead of default value
• Thinking it throws an error without Provider
• Confusing default value with null

4. Identify the error in this Next.js client component using React context:

import { createContext, useContext } from 'react';

const UserContext = createContext();

export default function UserName() {
  const user = useContext(UserContext);
  return <div>User: {user.name}</div>;
}

medium

A. UserContext is not wrapped with a Provider, so user is undefined causing error

B. useContext hook is used incorrectly; should pass a string

C. Missing import of React from 'react'

D. Cannot use context inside client components

Solution

1. Step 1: Check context default value and Provider usage

   UserContext is created without a default value and no Provider is shown wrapping UserName, so useContext returns undefined.

2. Step 2: Understand error cause

   Accessing user.name when user is undefined causes a runtime error.

3. Final Answer:

   UserContext is not wrapped with a Provider, so user is undefined causing error -> Option A

4. Quick Check:

   Undefined context value causes error accessing properties [OK]

Hint: Always wrap context consumers with Provider to avoid undefined errors [OK]

Common Mistakes:

• Assuming useContext needs a string argument
• Forgetting to wrap with Provider
• Thinking React import is mandatory in Next.js 13+ client components

5. You want to create a theme toggle in a Next.js client component using React context. Which approach correctly updates the theme value across components?

hard

A. Pass theme as a prop to every component without using context

B. Create ThemeContext with a fixed string; update theme by changing the string directly in components

C. Use useState inside each component separately without context to manage theme

D. Create a ThemeContext with state and provide toggle function via Provider; use useContext to read and update theme

Solution

1. Step 1: Understand state sharing with context

   To update theme globally, context must provide state and a function to toggle it, so all components share and update the same state.

2. Step 2: Evaluate other options

   Fixed string cannot update dynamically; separate useState per component does not share state; passing props everywhere defeats context purpose.

3. Final Answer:

   Create a ThemeContext with state and provide toggle function via Provider; use useContext to read and update theme -> Option D

4. Quick Check:

   Context with state and updater shares dynamic data [OK]

Hint: Use context Provider with state and updater for shared dynamic data [OK]

Common Mistakes:

• Trying to update fixed context value directly
• Using separate state in each component without sharing
• Passing props everywhere instead of using context