taro hook 倒计时setInterval版

let timer;
const Index = () => {
  const [count2, setCount2] = useState(0)
  useEffect(() => {
    timer && clearInterval(timer);
    return () => timer && clearInterval(timer);
  }, []);
  useEffect(() => {
    if (count2 === 10) {
      timer = setInterval(() => setCount2(c => --c), 1000) // 重点 一定要--c 因为先减才会出发useEffect

    }
    if (count2 === 0) {
      clearInterval(timer)
    }
  }, [count2])
  const onClick = () => {
    setCount2(10)
  }
  return (
    <View className='wrapper'>
      <View onClick={onClick}>{ count2? `${count2}秒后获取`: '获取验证码' }</View>
    </View>
  );
};