Function reducer

examples/files/app/todos.js:24–34

(state, action)

}

export function reducer(state, action) {
  switch (action.type) {
    case types.ADD:
      return { ...state, items: [...state.items, action.payload] }
    case types.REMOVE:
      return {
        ...state,
        items: state.items.filter((item) => item.id !== action.payload),
      }
  }
}