bashidagha

import { createStore } from "redux";
import { Provider } from "react-redux";
import Header from "./Header";

const initialState = { username: "Farshid" };
const returnStateReducer = (state = initialState, action) => {
 if (action.type === "updateUser") {
  return { ...state, username: "Farhad" };
 } else {
  return state;

bashidagha

const Header = ()=> {
  const user = useSelector((state) => state.username);
  return (
    <div>{user} </div>
  )
}
export default Header

bashidagha

import {createStore} from 'redux'
import {Provider} from 'react-redux'
import Header from './Header'

const initialState = {username : "Farshid"};
const returnStateReducer = (state= initialState) =>{
    return state;
}
const store =createStore(returnStateReducer);
const App= () => {

bashidagha

const Header = ()=> {
  return (
    <div> Header </div>
  )}
export default Header

bashidagha

import {createStore} from 'redux'
import {Provider} from 'react-redux'

const initialState = {username : "Farshid"};
const returnStateReducer = (state= initialState) =>{
    return state;
}
const store =createStore(returnStateReducer);
const App= () => {
  return (

bashidagha

import {createStore} from 'redux'

const initialState = {username : "Farshid"};
const returnStateReducer = (state= initialState) =>{
    return state;
  }
const store =createStore(returnStateReducer);
const App= () => {
  return (
      <div>

bashidagha

import {createStore} from 'redux'

const store =createStore();
const App= () => {
return (
      <div>
        <h1>Hello  World</h1>
      </div> 
  )
}

bashidagha

const App= () => {
return  <div><h1>Hello World</h1></div>
)}
export default  App;

bashidagha

import {useDispatch, useSelector} from 'react-redux'

const Header = ()=> {
  const user = useSelector((state) => state.username);
  const dispatch = useDispatch();

  return (
    <div>{user}
    <button onClick={()=> dispatch({type: "updateUser"})}>Change User</button>
    </div>

bashidagha

import {useDispatch, useSelector} from 'react-redux'

const Header = ()=> {
  const user = useSelector((state) => state.username);
  const dispatch = useDispatch();

  return (
    <div>{user}
    <input onChange={(e)=> dispatch({type: "updateMyName", payload: e.target.value}) }>
    </input>