Redux setup

App.js

import React, { Component } from 'react'
import store from './store.js'

class App extends Component {

  componentDidMount() {
    // subscribe to state changes -> forceUpdate will ask React to re-render the view
    this.unsubscribe = store.subscribe(() => this.forceUpdate())
  }

  componentWillUnmount() {
    // when component is removed from the view -> remove the subscription
    this.unsubscribe()
  }

  render() {
    const state = store.getState()
    
    return (
      <div className="App">
      </div>
    )
  }
}

reducer.js

const initialState = {}

// set initialState with default parameter value (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Default_parameters)
const reducer = (state = initialState, action) => {
  switch (action.type) {
    default: return state // ! always return a state object
  }
}

export default reducer

store.js

import { createStore } from 'redux'
import reducer from './reducer.js'

const store = createStore(reducer)

export default store