Persisting data with localStorage

If the data is serializable, it's fairly simple.

const getLocalStorage = (key) =>

JSON.parse(localStorage.getItem(key))

const setLocalStorage = (key) => (state) =>

localStorage.setItem(key, JSON.stringify(state))

// usage

const atom = create(getLocalStorage('foo') || initialState)

atom.subscribe(setLocalStorage('foo'))