redux counter

index.js

import { createStore } from 'redux';

const increment = () => ({
  type: 'INCREMENT',
});

const decrement = () => ({
  type: 'DECREMENT',
});

function counter(state = 0, action) {
  switch (action.type) {
    case 'INCREMENT':
      return state + 1;
    case 'DECREMENT':
      return state - 1;
    default:
      return state;
  }
}

const store = createStore(counter);

store.subscribe(() => console.log(store.getState()));

store.dispatch(increment());
store.dispatch(decrement())