js跨域调用iframe内容

// 服务器端（Node.js）
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
  res.header('Access-Control-Allow-Headers', 'Content-Type');
  next();
});

fetch('https://api.example.com/data')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));

<script>
function handleResponse(data) {
  console.log(data);
}
</script>
<script src="https://api.example.com/data?callback=handleResponse"></script>

// 服务器端（Node.js）
const express = require('express');
const request = require('request');

const app = express();

app.get('/proxy', (req, res) => {
  request('https://api.example.com/data', (error, response, body) => {
    if (!error && response.statusCode == 200) {
      res.send(body);
    }
  });
});

app.listen(3000);

fetch('/proxy')
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));

// 父页面
const iframe = document.getElementById('myIframe');
iframe.onload = () => {
  iframe.contentWindow.postMessage('Hello from parent', 'https://target-domain.com');
};

window.addEventListener('message', event => {
  if (event.origin !== 'https://target-domain.com') return;
  console.log(event.data);
});

// iframe页面（https://target-domain.com）
window.addEventListener('message', event => {
  if (event.origin !== 'https://parent-domain.com') return;
  console.log(event.data);
  event.source.postMessage('Hello from iframe', event.origin);
});