Run the application

1. Install Node To check the version

node -v

2. Install NPM Install using

npm install -g npm

To check the version

npm -v

3. Install expo on phone
4. Run Expo on console Go to the project directory and run:

npx expo start

4. Connect Scan barcode or input the number in console to the phone

Redux

1. Install redux

• npm

npm i react-redux @reduxjs/toolkit

• yarn

yarn add @reduxjs/toolkit react-redux

2. Create directory -reduceres

• index.js
• counter.js

3. index.js Configures the Redux store using configureStore from Redux Toolkit. It combines all reducers, in this case, only the counter reducer.

import { configureStore } from "@reduxjs/toolkit";
import counterReducer from './counter'

export default configureStore({
    reducer: {
        counter: counterReducer
    }
})

4. Counter.js Defines a Redux slice using createSlice from Redux Toolkit. This slice manages the state related to the counter, including its initial state and reducers for incrementing and decrementing the count.

import { createSlice } from "@reduxjs/toolkit";

const counterSlice = createSlice({
    name: 'counter',
    initialState: {
        count: 0,

    },
    reducers: {
        increment: (state) => {
            state.count += 1
        },
        decrement: (state) => {
            state.count -= 1
        }
    }
})

//export const { } = counterSlice.actions
export const counterActions = counterSlice.actions

export default counterSlice.reducer;

5. Inside page Import necessary dependencies from React Redux and the counter reducer.

mport { useDispatch, useSelector } from "react-redux"
import counter from "../reducers/counter"
import { counterActions } from "../reducers/counter"

Use useSelector hook to extract the count from the Redux store state and useDispatch hook to dispatch actions.

    const count = useSelector((state) => state.counter.count)
    const dispatch = useDispatch()

Display the count value and provide buttons to increment and decrement the count, dispatching respective actions when clicked.

            <Text>{count}</Text>
            <TouchableOpacity title='login' style={styles.button} onPress={() => dispatch(counterActions.increment())}>
                    <Text style={{color:'white'}} >increment</Text>
            </TouchableOpacity>
            <TouchableOpacity title='login' style={styles.button} onPress={() => dispatch(counterActions.decrement())}>
                    <Text style={{color:'white'}} >decrement</Text>
            </TouchableOpacity>

6. Extending Redux State to Multiple Screens By importing useSelector from "react-redux", you can access the count value from the counter slice of the Redux store. This allows you to display the count value on different screens of your application.

import { useSelector } from "react-redux"

Use the useSelector hook to extract the count value from the Redux store's state. This hook takes a selector function as an argument, which returns the desired part of the state. In this case, it retrieves the count value from the counter slice of the Redux store.

const count = useSelector((state) => state.counter.count)

You can then use the Text component from React Native to display the count value on your screen.

<Text>{count}</Text>