React子组件向父组件传递状态：使用回调函数与Hooks实现

import React, { useState, useEffect } from 'react';
import {
  Grid, Box, Card, CardContent, Typography,
  LinearProgress, ButtonGroup, ListItemButton,
  CardActions, Button
} from '@mui/material';
// 假设 useAxios 和 baseURL_Q 已经定义
// import useAxios from './hooks/useAxios';
// import { baseURL_Q } from './config';

import CountDown from './CountDown'; // 导入子组件

export default function QuestionCard() {
  const [questions, setQuestions] = useState([]);
  const [clickedIndex, setClickedIndex] = useState(0);
  const [currentQuestionIndex, setCurrentQuestionIndex] = useState(0);
  const [value, setValue] = useState(null);
  // 声明 onTime 状态，并初始化为 true
  const [onTime, setOnTime] = useState(true); 

  // 假设 useAxios 和 getQuestions 存在
  // const { isLoading, error, sendRequest: getQuestions } = useAxios();
  // const { sendRequest: getAnswers } = useAxios();

  // 模拟数据获取，实际应用中替换为 useAxios
  useEffect(() => {
    const fetchQuestions = () => {
      // 模拟异步数据
      setTimeout(() => {
        const mockQuestions = [
          { id: 'q1', id_test: 't1', tipologia_domanda: 'multi', testo: '这是第一个问题', immagine: null, eliminata: false },
          { id: 'q2', id_test: 't1', tipologia_domanda: 'multi', testo: '这是第二个问题', immagine: null, eliminata: false },
        ];
        setQuestions(mockQuestions);
      }, 500);
    };
    fetchQuestions();
  }, []); // 依赖数组为空，只在组件挂载时执行一次

  const handleSubmit = () => {
    setValue(true);
  };

  const handleSelectedItem = (index) => {
    setClickedIndex(index);
  };

  const handleChange = (e) => {
    setValue(e.target.value);
  };

  const goToNext = () => {
    setCurrentQuestionIndex((prevIndex) => (prevIndex + 1) % questions.length);
    setValue(null); // 重置选项
    setClickedIndex(0); // 重置选中状态
  };

  let questionsTitle = questions.map((element) => `${element.testo}`);
  // let questionId = questions.map((element) => `${element.id}`); // 未使用，可移除

  return (
    <Grid container spacing={1}>
      <Grid item xs={10}>
        <Box
          sx={{
            minWidth: 275,
            display: 'flex',
            alignItems: 'center',
            justifyContent: 'center', // 居中显示
            paddingBottom: '5%',
            paddingTop: '5%', // 添加一些顶部填充
          }}
        >
          {/* 根据 onTime 状态条件渲染内容 */}
          {onTime ? (
            <Card
              variant='outlined'
              sx={{
                minWidth: 400,
              }}
            >
              <CardContent>
                <Grid container spacing={0}>
                  <Grid item xs={8}>
                    <Typography
                      variant='h5'
                      component='div'
                      fontFamily={'Roboto'}
                    >
                      Nome Test
                    </Typography>
                  </Grid>
                  <Grid item xs={4}>
                    {/* 将 setOnTime 函数作为 prop 传递给 CountDown */}
                    <CountDown seconds={30} setOnTime={setOnTime} />
                  </Grid>
                </Grid>

                <LinearProgress variant='determinate' value={1} />

                <Typography
                  sx={{ mb: 1.5, mt: 1.5 }}
                  fontFamily={'Roboto'}
                  fontWeight={'bold'}
                >
                  {questionsTitle[currentQuestionIndex]}
                </Typography>

                <ButtonGroup
                  fullWidth
                  orientation='vertical'
                  onClick={handleSubmit}
                  onChange={handleChange}
                >
                  <ListItemButton
                    selected={clickedIndex === 1}
                    onClick={() => handleSelectedItem(1)}
                  >
                    Risposta 1
                  </ListItemButton>
                  <ListItemButton
                    selected={clickedIndex === 2}
                    onClick={() => handleSelectedItem(2)}
                  >
                    Risposta 2
                  </ListItemButton>
                  <ListItemButton
                    selected={clickedIndex === 3}
                    onClick={() => handleSelectedItem(3)}
                  >
                    Risposta 3
                  </ListItemButton>
                  <ListItemButton
                    selected={clickedIndex === 4}
                    onClick={() => handleSelectedItem(4)}
                  >
                    Risposta 4
                  </ListItemButton>
                </ButtonGroup>
              </CardContent>
              <CardActions>
                <Button onClick={goToNext} disabled={!value} variant='contained' size='small'>
                  Avanti
                </Button>
              </CardActions>
            </Card>
          ) : (
            <Typography variant='h4' color='error'>
              时间已到！
            </Typography>
          )}
        </Box>
      </Grid>
    </Grid>
  );
}

import { Typography, Paper, Grid } from '@mui/material';
import React, { useEffect, useRef, useState } from 'react';

const formatTime = (time) => {
  let minutes = Math.floor(time / 60);
  let seconds = Math.floor(time - minutes * 60);

  // 格式化为两位数
  minutes = minutes < 10 ? '0' + minutes : minutes;
  seconds = seconds < 10 ? '0' + seconds : seconds;

  return minutes + ':' + seconds;
};

function CountDown(props) {
  const [countdown, setCountdown] = useState(props.seconds);
  // 移除组件内部的 onTime 状态
  // const [onTime, setOnTime] = useState(true); 
  const timertId = useRef();

  // 计时器启动逻辑
  useEffect(() => {
    timertId.current = setInterval(() => {
      setCountdown((prev) => prev - 1);
    }, 1000);

    // 清理函数：组件卸载时清除计时器
    return () => clearInterval(timertId.current);
  }, []); // 依赖数组为空，只在组件挂载时执行一次

  // 倒计时结束逻辑
  useEffect(() => {
    if (countdown <= 0) {
      clearInterval(timertId.current); // 停止计时器
      // 调用父组件传递的 setOnTime 函数更新父组件状态
      props.setOnTime(false); 
    }
  }, [countdown, props.setOnTime]); // 依赖 countdown 和 props.setOnTime

  return (
    <Grid container>
      <Grid item xs={5}>
        <Paper elevation={0} variant='outlined' square>
          <Typography component='h6' fontFamily={'Roboto'}>
            Timer:
          </Typography>
        </Paper>
      </Grid>
      <Grid item xs={5}>
        <Paper
          elevation={0}
          variant='outlined'
          square
          sx={{ bgcolor: 'lightblue' }}
        >
          <Typography component='h6' fontFamily={'Roboto'}>
            {formatTime(countdown)}
          </Typography>
        </Paper>
      </Grid>
    </Grid>
  );
}

export default CountDown;