钩子函数

• starting with use
• can only call Hooks at the top of your components

useRef()

• 访问DOM，如获取焦点

const form = useRef();

<form ref={form} onSubmit={sendEmail}></form>

useEffect()

useReducer()

useContext()

useMemo()

useCallback()

1. Lorem ipsum dolor sit amet.
2. Dicta omnis laudantium officiis eaque!
3. Expedita quod distinctio nulla laboriosam?

1. Lorem ipsum dolor sit amet.
2. Dicta omnis laudantium officiis eaque!
3. Expedita quod distinctio nulla laboriosam?