Consuming context in React - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to consume context using the correct hook.

React

const value = React.[1](MyContext);

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

AuseState

BuseEffect

CuseContext

DuseRef

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState or useEffect instead of useContext.

Trying to access context without a hook.

The useContext hook is used to consume a React context value inside a functional component.

2fill in blank

medium

Complete the code to import the hook needed to consume context.

React

import React, { [1] } from 'react';

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

AuseEffect

BuseContext

CuseState

DuseMemo

Attempts:

3 left

💡 Hint

Common Mistakes

Importing useState or useEffect instead of useContext.

Forgetting to import the hook.

You need to import useContext from React to consume context inside a functional component.

3fill in blank

hard

Fix the error in consuming context by filling the blank with the correct context variable.

React

const theme = useContext([1]);

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

AThemeContext

BThemeProvider

Ctheme

DuseTheme

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the provider component instead of the context object.

Passing a hook name or variable instead of the context.

You must pass the context object (usually named ThemeContext) to useContext, not the provider or a hook.

4fill in blank

hard

Fill both blanks to consume context and display its value.

React

const value = [1]([2]);
return <div>{value}</div>;

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

AuseContext

BuseState

CMyContext

DThemeProvider

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState instead of useContext.

Passing the provider instead of the context object.

Use useContext with the context object (e.g., MyContext) to get the current context value.

5fill in blank

hard

Fill all three blanks to consume context and use it in a component.

React

import React, { [1] } from 'react';

function MyComponent() {
  const value = [2]([3]);
  return <p>{value}</p>;
}

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

AuseContext

BuseState

CMyContext

DThemeProvider

Attempts:

3 left

💡 Hint

Common Mistakes

Importing or using the wrong hook.

Passing the provider or other variables instead of the context object.

Import useContext, then use it with the context object MyContext to get the context value inside the component.

Practice

1. What is the primary purpose of using useContext in React?

easy

A. To fetch data from an API

B. To create a new context object

C. To update the state of a component

D. To read shared data from a context inside a component

Solution

1. Step 1: Understand the role of useContext

   useContext is a React hook used to access data from a context object inside a component.

2. Step 2: Differentiate from other hooks

   It does not create context or update state; it only reads the shared data provided by a context.

3. Final Answer:

   To read shared data from a context inside a component -> Option D

4. Quick Check:

   useContext reads context data [OK]

Hint: useContext reads shared data inside components [OK]

Common Mistakes:

• Confusing useContext with creating context
• Thinking useContext updates state
• Using useContext to fetch API data

2. Which of the following is the correct syntax to consume a context named ThemeContext inside a functional component?

easy

A. const theme = useContext(ThemeContext);

B. const theme = ThemeContext.useContext();

C. const theme = useContext();

D. const theme = ThemeContext();

Solution

1. Step 1: Recall the correct useContext syntax

   The hook useContext is called with the context object as an argument: useContext(ThemeContext).

2. Step 2: Identify incorrect options

   Options A, B, and D misuse the hook or context object syntax.

3. Final Answer:

   const theme = useContext(ThemeContext); -> Option A

4. Quick Check:

   useContext requires context object as argument [OK]

Hint: Pass context object inside useContext() [OK]

Common Mistakes:

• Calling useContext without argument
• Using context object as a function
• Trying to call useContext as a method on context

3. Given this code snippet, what will be logged to the console?

const UserContext = React.createContext('Guest');

function DisplayUser() {
  const user = React.useContext(UserContext);
  console.log(user);
  return <div>Hello, {user}!</div>;
}

function App() {
  return (
    <UserContext.Provider value="Alice">
      <DisplayUser />
    </UserContext.Provider>
  );
}

medium

A. "Guest"

B. "Alice"

C. undefined

D. Error: Context not found

Solution

1. Step 1: Identify the context default and provider value

   The default value is "Guest" but the Provider sets the value to "Alice".

2. Step 2: Understand useContext behavior inside Provider

   Since DisplayUser is inside the Provider, it receives the value "Alice" from context.

3. Final Answer:

   "Alice" -> Option B

4. Quick Check:

   Provider value overrides default context [OK]

Hint: Provider value overrides default context value [OK]

Common Mistakes:

• Assuming default context value is always used
• Thinking useContext returns undefined without explicit value
• Confusing Provider and Consumer roles

4. What is the error in the following code that tries to consume a context?

const LanguageContext = React.createContext('English');

function Greeting() {
  const language = useContext(LanguageContext);
  return <h1>Hello in {language}</h1>;
}

function App() {
  return <Greeting />;
}

medium

A. LanguageContext must be a function, not an object

B. Greeting component must be a class component

C. useContext is not imported or defined

D. Context value must be passed as a prop

Solution

1. Step 1: Check useContext usage

   The code uses useContext but does not import or prefix it with React.

2. Step 2: Identify missing import or reference

   Without importing useContext from React or using React.useContext, this causes a ReferenceError.

3. Final Answer:

   useContext is not imported or defined -> Option C

4. Quick Check:

   useContext must be imported or accessed via React [OK]

Hint: Always import or prefix useContext with React [OK]

Common Mistakes:

• Forgetting to import useContext
• Using useContext without React prefix or import
• Assuming context value passed as prop automatically

5. You have a nested component structure where ThemeContext provides a value at the top level. You want to consume this context in a deeply nested component without passing props through intermediate components. Which approach correctly achieves this?

hard

A. Wrap the nested component tree with ThemeContext.Provider and use useContext(ThemeContext) inside the nested component

B. Pass the context value as props through every intermediate component until it reaches the nested component

C. Use useContext in the nested component without wrapping the tree in ThemeContext.Provider

D. Create a new context inside the nested component and use useContext on it

Solution

1. Step 1: Understand context provider role

   The ThemeContext.Provider must wrap the component tree to supply the context value.

2. Step 2: Consume context in nested component

   Inside the nested component, useContext(ThemeContext) reads the value without needing props passed down.

3. Final Answer:

   Wrap the nested component tree with ThemeContext.Provider and use useContext(ThemeContext) inside the nested component -> Option A

4. Quick Check:

   Provider wraps tree; useContext reads value [OK]

Hint: Wrap tree with Provider, consume with useContext inside [OK]

Common Mistakes:

• Trying to use useContext without Provider
• Passing props through all components instead of context
• Creating new context inside nested component