React-typescript中ref定義

示例：

　　

const Home: React.FC = () => {
    const textRef = useRef<HTMLInputElement & HTMLTextAreaElement>(null);

    useEffect(() => {
        console.log(textRef.current && textRef.current.value.indexOf('\n'));
    }, []);

    return (
        <div className='home'>
            <header className='home-header'>
                <Header />
            </header>
            <main className='home-main'>
                <aside></aside>
                <article>
                    <textarea ref={textRef as React.RefObject<HTMLTextAreaElement>} defaultValue='撒大蘇打實打實廣發而高盛公司的發生法發案說法沙俄噶爾'></textarea>
                </article>
            </main>
        </div>
    );
};

export default Home;