js如何访问跨域的url

app.use((req, res, next) => {
  res.header("Access-Control-Allow-Origin", "*"); // 允许所有域，或指定特定域如"http://example.com"
  res.header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
  next();
});

<script>
function handleResponse(response) {
    console.log('跨域数据：', response);
}
</script>
<script src="http://example.com/data?callback=handleResponse"></script>

app.get('/data', (req, res) => {
    const callback = req.query.callback;
    const data = { message: 'Hello from server!' };
    res.send(`${callback}(${JSON.stringify(data)})`);
});

const { createProxyMiddleware } = require('http-proxy-middleware');

app.use('/api', createProxyMiddleware({
  target: 'http://example.com',
  changeOrigin: true,
  pathRewrite: {
    '^/api': '' // 重写路径
  }
}));

const socket = new WebSocket('ws://example.com/socketserver');

socket.onmessage = function(event) {
    console.log('Message from server ', event.data);
};