simple one level immutable store object

store.js

const store = {
  storageIndex: undefined,
  debug: false,
  state: Object.freeze({
  }),
  setState(keyword, value) {
    if (this.debug) console.log(`STATE: ${keyword}:`, value); // eslint-disable-line no-console
    const newObject = Object.assign({}, this.state, { [keyword]: value });
    this.state = Object.freeze(newObject);
    if (this.storageIndex) localStorage.setItem(this.storageIndex, JSON.stringify(newObject));
  },
  fillState(obj) {
    this.state = Object.freeze(Object.assign({}, obj));
    if (this.storageIndex) localStorage.setItem(this.storageIndex, JSON.stringify(this.state));
  },
  load() {
    if (this.storageIndex) {
      const storedStuff = localStorage.getItem(this.storageIndex);

      if (storedStuff && storedStuff.length) {
        this.fillState(Object.freeze(JSON.parse(storedStuff)));
      }
    }
  }
};

export default store;

usage-example.js

import store from './store'

store.storageIndex = 'family-guy-reverse-puke'
store.debug = true
store.load()


const viewModel = ({store}) => {
  	store.setState('clicked', 0)
  
  	document.addEventListener('click', e => {
    	store.setState('clicked', store.state.clicked + 1)
	})	
}

new viewModel({store})