Avoiding prop drilling in React - Mini Project: Build & Apply

Avoiding Prop Drilling in React with Context

📖 Scenario: You are building a simple React app that shows a user's favorite color in a deeply nested component. Instead of passing the color through many layers of components (which is called prop drilling), you will use React Context to share the color easily.

🎯 Goal: Build a React app that uses Context to provide a favorite color value to a nested component without passing it through intermediate components as props.

📋 What You'll Learn

Create a React Context to hold the favorite color

Provide the favorite color value at the top level using Context.Provider

Consume the favorite color value in a deeply nested component using useContext hook

Avoid passing the favorite color as props through intermediate components

💡 Why This Matters

🌍 Real World

In real apps, data like user info, theme, or language often needs to be accessed by many components. Using React Context helps avoid passing props through many layers, making code cleaner and easier to maintain.

💼 Career

Understanding how to avoid prop drilling with React Context is a key skill for frontend developers building scalable React applications.

1

Create the favorite color data and Context

Create a constant called favoriteColor and set it to the string 'blue'. Then create a React Context called ColorContext using React.createContext().

React

import React from 'react';

// Create favoriteColor and ColorContext here
# Your code here

Hint

Use const favoriteColor = 'blue' and const ColorContext = React.createContext().

2

Provide the favorite color using Context.Provider

Create a functional component called App. Inside it, return ColorContext.Provider with the value prop set to favoriteColor. Inside the provider, render a component called Parent.

React

import React from 'react';

const favoriteColor = 'blue';
const ColorContext = React.createContext();

// Create App component with ColorContext.Provider and render Parent inside
# Your code here

Hint

Wrap Parent with ColorContext.Provider and set value={favoriteColor}.

3

Create nested components without passing props

Create two functional components: Parent and Child. Parent should return <Child />. Child will later consume the context. Do not pass any props between them.

React

import React from 'react';

const favoriteColor = 'blue';
const ColorContext = React.createContext();

function App() {
  return (
    
      
    
  );
}

// Create Parent and Child components here
# Your code here

Hint

Create Parent returning <Child /> and an empty Child component.

4

Consume the favorite color in Child using useContext

In the Child component, use the useContext hook with ColorContext to get the favorite color. Return a <div> that says Your favorite color is {color}, where color is the value from context.

React

import React from 'react';

const favoriteColor = 'blue';
const ColorContext = React.createContext();

function App() {
  return (
    
      
    
  );
}

function Parent() {
  return ;
}

function Child() {
  // Use useContext to get color and return div
  # Your code here
}

Hint

Import useContext and use it inside Child to get the color from ColorContext.

Practice

1. What is the main problem that prop drilling causes in React applications?

easy

A. Not using hooks properly in functional components

B. Using too many state variables in a single component

C. Rendering components multiple times unnecessarily

D. Passing props through many layers even if intermediate components don't need them

Solution

1. Step 1: Understand what prop drilling means

   Prop drilling happens when props are passed down through many components that don't use them, just to reach a deeply nested component.

2. Step 2: Identify the main issue caused by prop drilling

   This makes the code harder to maintain and understand because many components receive props they don't need.

3. Final Answer:

   Passing props through many layers even if intermediate components don't need them -> Option D

4. Quick Check:

   Prop drilling = Passing props through many layers [OK]

Hint: Prop drilling means unnecessary passing props down layers [OK]

Common Mistakes:

• Confusing prop drilling with state management issues
• Thinking prop drilling is about rendering performance
• Believing prop drilling is caused by hooks misuse

2. Which of the following is the correct way to create a React Context to avoid prop drilling?

easy

A. const MyContext = React.useContext();

B. const MyContext = React.createContext();

C. const MyContext = React.useState();

D. const MyContext = React.useEffect();

Solution

1. Step 1: Recall the React API for creating context

   React provides createContext to create a context object for sharing data.

2. Step 2: Identify the correct syntax

   The correct syntax is const MyContext = React.createContext();. The other options are hooks used for different purposes.

3. Final Answer:

   const MyContext = React.createContext(); -> Option B

4. Quick Check:

   createContext() creates context [OK]

Hint: Use createContext() to make a context object [OK]

Common Mistakes:

• Using useContext() to create context instead of consume it
• Confusing useState() or useEffect() with context creation
• Missing parentheses after createContext

3. Given this code snippet, what will be the output inside Child component?

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

function Parent() {
  return (
    
      
    
  );
}

function Child() {
  const value = React.useContext(MyContext);
  return <div>{value}</div>;
}

medium

A. <div>hello</div>

B. <div>default</div>

C. <div>undefined</div>

D. Error: useContext must be inside a Provider

Solution

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

   The context default is 'default', but the Parent component provides the value 'hello' via MyContext.Provider.

2. Step 2: Determine what useContext returns inside Child

   The Child component uses useContext(MyContext), so it receives the nearest provider's value, which is 'hello'.

3. Final Answer:

   <div>hello</div> -> Option A

4. Quick Check:

   useContext returns nearest Provider value [OK]

Hint: useContext gets nearest Provider value, not default [OK]

Common Mistakes:

• Assuming default value is always used
• Thinking useContext returns undefined without explicit value
• Confusing Provider value with component props

4. Identify the error in this code that tries to avoid prop drilling using React Context:

const MyContext = React.createContext();

function Parent() {
  const value = 'data';
  return <Child />;
}

function Child() {
  const value = React.useContext(MyContext);
  return <div>{value}</div>;
}

medium

A. MyContext.Provider is missing around Child component

B. useContext is used incorrectly inside Child

C. createContext must have a default value

D. Parent should pass value as a prop to Child

Solution

1. Step 1: Check if Provider wraps components needing context

   The Parent component returns <Child /> without wrapping it in MyContext.Provider.

2. Step 2: Understand useContext requires Provider to get value

   Without a Provider, useContext(MyContext) returns the default value, which is undefined here, likely not intended.

3. Final Answer:

   MyContext.Provider is missing around Child component -> Option A

4. Quick Check:

   Provider missing = context value undefined [OK]

Hint: Always wrap consumers with Provider to supply context [OK]

Common Mistakes:

• Thinking createContext must have default value
• Believing useContext works without Provider
• Confusing prop passing with context usage

5. You have a deeply nested component tree where ThemeContext provides a theme string. You want to avoid prop drilling and also allow components to update the theme. Which approach correctly combines context and state to achieve this?

hard

A. Use multiple contexts for theme and setTheme separately and pass them as props

B. Pass theme as a prop from top to bottom and use useState only in the deepest component

C. Create ThemeContext with createContext, provide {theme, setTheme} from a state in a top-level component, and consume both in nested components

D. Store theme in a global variable and read it directly in nested components

Solution

1. Step 1: Understand how to share state and updater via context

   To avoid prop drilling and allow updates, the context should provide both the current value and a function to update it.

2. Step 2: Use createContext and provide state and setter from top-level

   Create a context with createContext(), then in a top-level component use useState to hold theme and pass both theme and setTheme in the Provider's value.

3. Step 3: Consume both theme and setTheme in nested components

   Nested components use useContext to get both and can read or update the theme without prop drilling.

4. Final Answer:

   Create ThemeContext with createContext, provide {theme, setTheme} from a state in a top-level component, and consume both in nested components -> Option C

5. Quick Check:

   Context with state and setter avoids prop drilling [OK]

Hint: Provide state and setter in context value to update data [OK]

Common Mistakes:

• Passing only value without setter in context
• Using global variables instead of React state
• Passing props through many layers instead of context