js得到request中的值

const express = require('express');
const app = express();
app.use(express.json()); // 用于解析JSON格式的请求体

app.post('/endpoint', (req, res) => {
  const data = req.body; // 获取POST请求体中的数据
  console.log(data);
  res.send('Data received');
});

app.get('/endpoint', (req, res) => {
  const queryParam = req.query.paramName; // 获取GET请求中的查询参数
  console.log(queryParam);
  res.send('Query parameter received');
});

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

fetch('/endpoint', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({ key: 'value' })
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error('Error:', error));

var xhr = new XMLHttpRequest();
xhr.open('POST', '/endpoint', true);
xhr.setRequestHeader('Content-Type', 'application/json');
xhr.onload = function() {
  if (xhr.status === 200) {
    var data = JSON.parse(xhr.responseText);
    console.log(data);
  }
};
xhr.send(JSON.stringify({ key: 'value' }));