plain redux

redux.js

const redux = require('redux');

// * declaring initial state
const initialState = {
  counter: 0,
};

// * reducer
const rootReducer = (state = initialState, action) => {
  if (action.type === 'INC_COUNTER') {
    state.counter += 1;
  } else if (action.type === 'ADD_COUNTER') {
    state.counter += action.value;
  }
  return state;
};

// * store
const store = redux.createStore(rootReducer);
console.log(store.getState());

// * subscription
store.subscribe(() => {
  console.log(`[Subscription]`, store.getState());
});

// * dispatching action
store.dispatch({ type: 'INC_COUNTER' });
store.dispatch({ type: 'ADD_COUNTER', value: 10 });
console.log(store.getState());