CORS 预检通道中的 CORS 标头“Access-Control-Allow-Headers”中缺少令牌“access-control-allow-head

CORS 预检通道中的 Access-Control-Allow-Headers 缺少令牌

javascript
// Node.js Express 服务器端代码示例
const express = require('express');
const app = express();
app.options('/api', (req, res) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST');
  // 缺少了下面这行代码，导致预检请求的响应中缺少了 "access-control-allow-headers" 令牌
  // res.header('Access-Control-Allow-Headers', 'Content-Type');
  res.sendStatus(200);
});
app.post('/api', (req, res) => {
  // 处理跨域请求
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Content-Type', 'application/json');
  res.send(JSON.stringify({ message: '跨域请求成功' }));
});
app.listen(3000, () => {
  console.log('服务器已启动');
});

javascript
app.options('/api', (req, res) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST');
  res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization');
  res.sendStatus(200);
});