setStore = (storeName, key, value) => {
  if (localStorage.getItem(storeName)) {
    const prevObj = JSON.parse(localStorage.getItem(storeName));
    prevObj[key] = value;
    localStorage.setItem(storeName, JSON.stringify(prevObj));
  } else {
    const newObj = {};
    newObj[key] = value;
    localStorage.setItem(storeName, JSON.stringify(newObj));
  }
  return true;
}
Set a given (key, value) to a given store.
@param {String} storeName the name of the store, note that the name can be pageName
@param {String} key       the name of the key which is to be added. If the key is
present then it overwritten.
@param {String} value     the value for the given key.