尝试使用字符串作为有效负载来执行http.post请求

const payload = "Hello, World!"; // 字符串有效负载

fetch('http://example.com/api', {
  method: 'POST',
  body: payload
})
  .then(response => response.json())
  .then(data => {
    // 处理响应数据
    console.log(data);
  })
  .catch(error => {
    // 处理错误
    console.error(error);
  });

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

app.post('/api', (req, res) => {
  const payload = req.body; // 字符串有效负载
  // 处理有效负载
  console.log(payload);
  res.send('OK');
});

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