Context provider in React - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a context using React.

React

import React from 'react';
const MyContext = React.[1]();

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

AuseEffect

BuseState

CuseContext

DcreateContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState instead of createContext

Using useContext to create context

React's createContext function is used to create a new context object.

2fill in blank

medium

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

React

function MyProvider({ children }) {
  const value = { user: 'Alice' };
  return <MyContext.[1] value={value}>{children}</MyContext.[1]>;
}

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

AWrapper

BConsumer

CProvider

DContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using Consumer instead of Provider to pass values

Using Context or Wrapper which are not valid components

The Provider component of the context is used to pass the value down to children.

3fill in blank

hard

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

React

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

function User() {
  const context = [1](MyContext);
  return <div>{context.user}</div>;
}

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

AuseState

BuseContext

CuseEffect

DuseRef

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState or useEffect to read context

Not importing useContext from React

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

4fill in blank

hard

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

React

const ThemeContext = React.[1]('light');

function App() {
  return <ThemeContext.[2] value="dark">Content</ThemeContext.[2]>;
}

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

AcreateContext

BuseContext

CProvider

DConsumer

Attempts:

3 left

💡 Hint

Common Mistakes

Using Consumer instead of Provider to pass value

Using useContext to create context

Use createContext to create the context with a default value, and Provider to pass a new value.

5fill in blank

hard

Fill all three blanks to consume context and display its value inside a component.

React

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

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

function DisplayLanguage() {
  const language = [2](LanguageContext);
  return <p>Current language: [3]</p>;
}

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

AuseContext

BuseState

Clanguage

DuseEffect

Attempts:

3 left

💡 Hint

Common Mistakes

Using useState or useEffect instead of useContext

Trying to display the hook call instead of the variable

Import and use useContext to get the context value, then display the variable language.

Practice

1. What is the main purpose of a Context.Provider in React?

easy

A. To share data with all components inside its tree without passing props manually

B. To create a new React component

C. To handle component state locally

D. To style components globally

Solution

1. Step 1: Understand what Context.Provider does

   It allows sharing data to all nested components without passing props down manually.

2. Step 2: Compare options

   Only To share data with all components inside its tree without passing props manually describes this sharing behavior correctly; others describe unrelated tasks.

3. Final Answer:

   To share data with all components inside its tree without passing props manually -> Option A

4. Quick Check:

   Context.Provider shares data = A [OK]

Hint: Context.Provider shares data down component tree [OK]

Common Mistakes:

• Thinking Provider creates components
• Confusing Provider with state management
• Assuming Provider styles components

2. Which of the following is the correct way to create a context and provide a value in React?

easy

A. const MyContext = React.createContext(); ...

B. const MyContext = React.useContext(); ...

C. const MyContext = React.createProvider(); ...

D. const MyContext = React.createContext(); ...

Solution

1. Step 1: Identify correct context creation method

   React.createContext() is the correct method to create a context.

2. Step 2: Confirm correct usage of Provider

   Provider uses a value prop to share data; Consumer does not accept value prop directly.

3. Final Answer:

   const MyContext = React.createContext(); <MyContext.Provider value={data}>...</MyContext.Provider> -> Option D

4. Quick Check:

   createContext + Provider with value = D [OK]

Hint: Use React.createContext() and Provider with value prop [OK]

Common Mistakes:

• Using React.useContext() to create context
• Trying React.createProvider() which doesn't exist
• Passing value to Consumer instead of Provider

3. Given the code below, what will be rendered inside DisplayUser component?

const UserContext = React.createContext();

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

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

medium

A. Hello, undefined!

B. Error: useContext must be inside a Provider

C. Hello, Alice!

D. Hello, {user.name}!

Solution

1. Step 1: Check Provider value

   The Provider passes an object with name 'Alice' as value.

2. Step 2: useContext reads the value

   DisplayUser uses useContext to get the user object and accesses user.name which is 'Alice'.

3. Final Answer:

   Hello, Alice! -> Option C

4. Quick Check:

   useContext reads Provider value = B [OK]

Hint: useContext gets value from nearest Provider [OK]

Common Mistakes:

• Assuming useContext returns undefined without Provider
• Thinking useContext returns the whole context object, not value
• Confusing JSX output with raw code

4. Identify the error in the following React code using Context Provider:

const ThemeContext = React.createContext();

function App() {
  return (
    <ThemeContext.Provider>
      <Content />
    </ThemeContext.Provider>
  );
}

function Content() {
  const theme = React.useContext(ThemeContext);
  return <div>Theme is {theme}</div>;
}

medium

A. Provider is missing the required value prop

B. useContext is used incorrectly outside Provider

C. ThemeContext should be created with React.useContext()

D. Content component should not use useContext

Solution

1. Step 1: Check Provider usage

   The Provider must have a value prop to supply data to consumers.

2. Step 2: Identify missing value prop

   In the code, <ThemeContext.Provider> lacks value, so useContext gets undefined.

3. Final Answer:

   Provider is missing the required value prop -> Option A

4. Quick Check:

   Provider needs value prop = C [OK]

Hint: Provider always needs a value prop [OK]

Common Mistakes:

• Forgetting to pass value to Provider
• Confusing createContext with useContext
• Thinking useContext can't be inside Provider tree

5. You want to share a user object and a function to update it across many components using React Context. Which approach correctly combines these in a single context provider?

hard

A. Create two separate contexts, one for user and one for setUser; use two Providers

B. Create context with React.createContext(); provide value={{ user, setUser }}; consume with useContext

C. Pass user as value and call setUser directly inside components without context

D. Use useState inside each component instead of context

Solution

1. Step 1: Understand combining data and updater in context

   Context value can be an object holding both user data and setUser function.

2. Step 2: Confirm correct usage

   Providing value={{ user, setUser }} allows any component to read user and update it via setUser.

3. Final Answer:

   Create context with React.createContext(); provide value={{ user, setUser }}; consume with useContext -> Option B

4. Quick Check:

   Combine data and updater in one context value = A [OK]

Hint: Put data and updater together in context value object [OK]

Common Mistakes:

• Creating multiple contexts unnecessarily
• Calling setUser without context
• Using local state instead of shared context