Simple API for saving and retrieving data from local storage of browser

localStorage.js

// returns object which is persisted in local storage
const getState = () => {
  try {
    const serializedState = localStorage.getItem('state');
    if (serializedState === null) {
      return undefined;
    }
    return JSON.parse(serializedState);
  } catch (err) {
    return undefined;
  }
}

// overwrite new state
const saveState = (state) => {
  try {
    const serializedState = JSON.stringify(state);
    localStorage.setItem('state', serializedState);
  } catch (err) {
    // do something with write error.
  }
}

// example
const state = {
  firstname: 'John',
  lastname: 'Doe',
}

saveState(state);

// later
const storageData = getState();

console.log(storageData.firstname);
console.log(storageData.lastname);