simple example of how redux works

sample_redux.js

import {createStore} from 'redux';

// STORE -> GLOBALIZED STATE

// ACTION
// like restaurant menu
const increment = () => {
  return {
    type: 'INCREMENT'
  }
}
const decrement = () => {
  return {
    type: 'DECREMENT'
  }
}

// REDUCER  (how your action transfrom to other action)
// Like the kitchen in the restaurant, base on the order to cook food for customer
const counter = (state = 0, action) => {
  switch(action.type){
    case 'INCREMENT':
      return state + 1;
    case 'DECREMENT':
      return state - 1;
  }
}

let store = createStore(counter);

// print data to browser console
store.subscribe(() => console.log(store.getState()));

// DISPATCH (execute the action)
// like you order some food from the menu
store.dispatch(increment());  // => 1
store.dispatch(decrement());  // => 0