Access-Control-Allow-Origin 不允许 XMLHttpRequest 无法加载 Origin

Javascript
const express = require('express');
const app = express();
// 启用CORS中间件
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*'); // 允许所有域访问，实际应用中应根据需求进行配置
  res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE');
  res.header('Access-Control-Allow-Headers', 'Content-Type');
  next();
});
// 处理跨域请求的路由
app.get('/api/data', (req, res) => {
  // 处理你的逻辑并发送响应
  res.JSon({ message: 'Hello, CORS is enabled!' });
});
const port = 3000;
app.listen(port, () => {
  console.log(<code>Server is running on port ${port}</code>);
});