无法保存测验答案

<form action="/save-answer" method="POST">
  <input type="text" name="answer" id="answer">
  <button type="submit">提交</button>
</form>

<script>
document.querySelector('form').addEventListener('submit', function(event) {
  event.preventDefault();
  const answer = document.getElementById('answer').value;
  fetch('/save-answer', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ answer: answer })
  }).then(response => response.json())
    .then(data => console.log(data))
    .catch(error => console.error('Error:', error));
});
</script>

const express = require('express');
const bodyParser = require('body-parser');
const app = express();

app.use(bodyParser.json());

app.post('/save-answer', (req, res) => {
  const answer = req.body.answer;
  // 假设这里有一个saveToDatabase函数用于保存数据到数据库
  saveToDatabase(answer)
    .then(() => res.json({ success: true }))
    .catch(err => res.status(500).json({ error: err.message }));
});

function saveToDatabase(answer) {
  // 这里应该是实际的数据库操作代码
  return new Promise((resolve, reject) => {
    // 模拟数据库操作
    if (answer) {
      resolve();
    } else {
      reject(new Error('Answer is required'));
    }
  });
}

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

const express = require('express');
const cors = require('cors');
const app = express();

app.use(cors());
app.use(bodyParser.json());

// 其他路由和逻辑...