simple counter example ....

counter.js

import React from 'react';
import {render} from 'react-dom';
import {createStore} from 'redux'

const reducer = (state = 0 , action) =>  
  (action.type == 'inc' || action.type == 'dec') ? ((action.type == 'inc' ? state + 1 : state - 1) ) : state  

const store = createStore(reducer)

const Counter = ({value , onInc , onDec}) => (
  <div>
    <h1>{value}</h1>
    <button onClick={onInc}>+</button>
    <button onClick={onDec}>-</button>
  </div>
) 

const init = ()=> {
  render(<Counter value={store.getState()} onInc={()=> store.dispatch({type: 'inc'})} onDec={()=> store.dispatch({type: 'dec'})}/> , document.getElementById('root'))
}

init()

store.subscribe(init)