Using Redux Increment/Decrement with switch case

reducer.js

import React from 'react';
import ReactDOM from 'react-dom';
// import App from './App';

import { createStore } from 'redux';

const counterReducer = (state = 0,action) => {
switch(action.type){
  case 'INCREMENT':
    return state + 1
  case 'DECREMENT':
    return state - 1
  case 'ZERO':
    return 0
    default:
    return state
  }
}

const store = createStore(counterReducer)
console.log(store.getState())
store.dispatch({type:'INCREMENT'})
store.dispatch({type:'INCREMENT'})
store.dispatch({type:'INCREMENT'})
console.log(store.getState())
store.dispatch({type:'ZERO'})
store.dispatch({type:'DECREMENT'})
console.log(store.getState())

const App =()=>{
return <>hi</>
}
ReactDOM.render(
    <App />,
  document.getElementById('root')
);

/*
log outputs:
0 
 3 
-1*/