Best Practices for Managing Global State

Introduction

In this tutorial, we will learn the best practices for managing global state in your React applications using the Context API. We will explain how to avoid common pitfalls and make sure your code is efficient, maintainable, and scalable.

By the end of this tutorial, you will be able to:
- Understand the concept of global state.
- Use the Context API to manage global state in a React application.
- Learn and apply best practices for managing global state.

The prerequisites for this tutorial include a basic understanding of JavaScript and React.

Step-by-Step Guide

1. Understanding Global State

   Global state refers to the state that is accessible throughout the entire application. It's shared among all the components. In React, the Context API is primarily used to manage this global state.

2. Using the Context API

   The Context API is a component structure provided by the React framework, which allows us to share specific forms of data across all levels of the application. It's aimed at solving the problem of prop drilling.

   Here is a simple example of using the Context API:
   ```javascript
   // Create a Context
   const MyContext = React.createContext(defaultValue);

   // Provide the Context
   
   

   // Consume the Context
   
   {value => / render something based on the context value /}
   
   ```

3. Best Practices for Managing Global State

   • Avoid Overuse of Global State: Only use global state for data that's truly global. If a piece of data isn't needed by many parts of your app, consider keeping it in a local state instead.
   • Use Multiple Contexts: If you have data that changes together, then it’s great to combine it in a single context. But if you have data that changes independently, it’s better to have multiple contexts.
   • Combine Context with useReducer Hook: When your app state logic gets more complex, using the useReducer hook with context API can be a good combination.

Code Examples

1. Creating and Using Context

   Here's a basic example of creating Context and using it in a component. The ThemeContext provides a theme that can be used by all components:

   ```javascript
   // Create a Context
   const ThemeContext = React.createContext('light');

   // A component that uses the Context
   function ThemeButton() {
   const theme = useContext(ThemeContext);
   return ;
   }
   ``ThemeContextprovides a 'light' theme by default. TheThemeButtoncomponent uses theuseContexthook to consume the theme. If aThemeContext.Provider` is present somewhere above in the tree, it will use its value instead.

2. Combining Context with useReducer

   The useReducer hook can be used with Context to manage more complex state logic.

   ```javascript
   const initialState = {count: 0};

   function reducer(state, action) {
   switch (action.type) {
   case 'increment':
   return {count: state.count + 1};
   case 'decrement':
   return {count: state.count - 1};
   default:
   throw new Error();
   }
   }

   function Counter() {
   const [state, dispatch] = useReducer(reducer, initialState);
   return (
   <>
   Count: {state.count}
   dispatch({type: 'decrement'})}>-
   dispatch({type: 'increment'})}>+
   
   );
   }
   `` Here, we are using theuseReducerhook to manage state and actions. Thedispatch` function allows us to perform actions on the state.

Summary

In this tutorial, we learned how to manage global state in a React application using the Context API. We also learned some best practices for managing global state, such as avoiding overuse, using multiple contexts, and combining Context with the useReducer hook.

As next steps, you can explore other state management libraries like Redux or MobX. You can also learn more about the useReducer hook and how it can be used to manage complex state logic.

Practice Exercises

1. Create a simple React app that uses global state to manage a theme. The theme should be able to be toggled between 'light' and 'dark'.
2. Add a feature to the above app that counts the number of times the theme has been toggled. Use the useReducer hook to manage this state.
3. Add another feature to the app that fetches some data from an API and shares it across multiple components using global state.