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Chapter 4 : ConetextAPI & State

4. Context API & State Management​

a. Understanding the Context API:​

The Context API provides a way to share values between components without explicitly passing props through every level of the tree.

Task: Implement a basic authentication system where you can toggle between a logged-in state and a logged-out state using the Context API. Display different messages/components based on the current auth state.

b. Creating Context & Provider:​

Learn how to create a new context and a context provider that can wrap around parts of your app.

Task: Create a ThemeContext and a ThemeContextProvider component. This provider should wrap around parts of your app to provide them with theme-related functionalities.

c. useContext Hook:​

The useContext hook is a way to consume the context in functional components.

Task: Build a navigation bar that changes its color based on the current theme. Use the useContext hook to fetch the theme from the ThemeContext you created.

d. Dynamic Context:​

Understand how to update the context dynamically, reacting to events or user interactions.

Task: Extend the theme toggler project. Allow the user to choose between multiple themes (e.g., light, dark, blue, red) and dynamically update the context.

e. Using Context with useReducer:​

By using these together, you can mimic many features of more sophisticated state management libraries like Redux.

Task: Implement a simple product inventory system. Allow adding products to a cart and updating the inventory count. Use useReducer for the state logic and Context API to make the cart globally accessible.

f. Performance Considerations:​

It's crucial to understand when components re-render and how to optimize the context to prevent unnecessary renders.

Task: Using the React DevTools, inspect the re-rendering of components in your projects. Implement memoization or split contexts (if needed) to optimize renders.

g. Advanced Patterns:​

Explore advanced patterns like creating higher-order components (HOCs) or render props components that use the context for more advanced use cases.

Task: Create a HOC named withUser that fetches user data and provides it to wrapped components.

Project: User Settings Dashboard:​

  • Create a dashboard where users can update various settings like username, profile picture, theme, language, etc.
  • Use the Context API to store these settings.
  • Allow components across the app to access and react to these settings. For instance, if a user changes the language to Spanish, certain components should display content in Spanish.
  • Incorporate error handling and feedback mechanisms. If a user tries to set an unsupported language or theme, display an error message.

By focusing on these tasks, learners will obtain a comprehensive understanding of the Context API and its significance in state management, ensuring that they can architect React applications effectively with global state.