initialData: ResponseTodoType = { id: 0, userId: 0, title: "", completed: false, }; interface IResponse { data: ResponseTodoType | undefined; onChangeTitle: (value: string) => void; } export const useFetchTodo = (): IResponse => { const { data, mutate } = useFetch<ResponseTodoType>({ key: "/todos/1", fetcher: () => requestFetchTodo(1), }); const handleOnChangeTitle = useCallback((value: string) => { mutate((data = initialData) => { return { ...data, title: value }; }, false); }, []); return { data, onChangeTitle: handleOnChangeTitle, } as const; }; 1. ฤूରͷσʔλϑΣονॲཧ