**Course Title:** Building Mobile Applications with React Native **Section Title:** State Management with Redux **Topic:** Introduction to Redux and its Principles **Introduction** In the previous sections, we covered state management using React Hooks. While React Hooks are suitable for managing local component state, they can become cumbersome when dealing with global state that needs to be shared across multiple components. This is where Redux comes in – a predictable state container that helps you manage global state by providing a single source of truth for your application. **What is Redux?** Redux is a state management library that helps you manage global state by providing a single source of truth for your application. It was created by Dan Abramov and Andrew Clark in 2015 and has since become one of the most popular state management libraries in the JavaScript ecosystem. **Key Concepts** To understand Redux, you need to familiarize yourself with the following key concepts: 1. **Store**: The store is the central location that holds the entire state of your application. 2. **Actions**: Actions are payloads that trigger state changes in your application. They are typically dispatched by components. 3. **Reducers**: Reducers are pure functions that take the current state and an action, and return a new state. 4. **State**: State refers to the current state of your application. **The Redux Flow** Here's a step-by-step explanation of the Redux flow: 1. **Dispatch an action**: A component dispatches an action, which is a payload that triggers a state change. 2. **Reducer handles the action**: The reducer function takes the current state and the action, and returns a new state. 3. **State is updated**: The new state is updated in the store. 4. **Components are re-rendered**: Components that subscribe to the state changes are re-rendered with the new state. **Principles of Redux** Redux is built on three fundamental principles: 1. **Single source of truth**: The store holds the entire state of your application, making it the single source of truth. 2. **State is read-only**: State is read-only, meaning that it cannot be changed directly. Instead, components dispatch actions to trigger state changes. 3. **Changes are made with pure functions**: Reducers are pure functions that take the current state and an action, and return a new state. **Why Use Redux?** Redux provides several benefits, including: 1. **Predictable behavior**: Redux helps you manage global state in a predictable way, making it easier to debug and maintain your application. 2. **Decoupling**: Redux decouples your components from the state, making it easier to reuse and test components. 3. **Scalability**: Redux makes it easy to scale your application by providing a single source of truth for your state. **Real-World Example** Suppose you're building a shopping cart application. You have multiple components that need to access the cart state. With Redux, you can create a single store that holds the cart state, and dispatch actions to update the state when the user adds or removes items from the cart. **Code Example** Here's a simple example of a Redux store that manages a counter: ```jsx // actions.js export const INCREMENT = 'INCREMENT'; export const DECREMENT = 'DECREMENT'; export function increment() { return { type: INCREMENT }; } export function decrement() { return { type: DECREMENT }; } // reducers.js const initialState = 0; export default function counterReducer(state = initialState, action) { switch (action.type) { case INCREMENT: return state + 1; case DECREMENT: return state - 1; default: return state; } } // store.js import { createStore } from 'redux'; import counterReducer from './reducers'; const store = createStore(counterReducer); export default store; ``` In the next topic, we'll cover **Setting up Redux in a React Native project**. We'll learn how to integrate Redux into a React Native project, and use it to manage global state. **Leave a comment or ask for help** If you have any questions or need help with understanding the concepts covered in this topic, please leave a comment below. **Additional Resources** * [Redux Official Documentation](https://redux.js.org/) * [Redux Example Apps](https://redux.js.org/introduction/examples) * [React Native Redux Example](https://github.com/academind/react-native-redux-example)