handler.js

const handleSelectUpdate = (target) => {
  return { [target.name]: target.value };
};

handleChosenCountry: (state, target) =>
  const selectState = handleSelectUpdate(target);
  const newState = handleChosenCountry(state, target.value)

  handleFetchEvents({ ...state, chosenCountry: selectState.country }).then(res => {
    store.setState({ 
      ...state,
      ...newState,
      events: res.data,
     });
  });