<html>
<body>
<script type="text/javascript" charset="utf-8">
  const {ipcRenderer} = require('electron')
  const popup = window.open('native-window-open-child.html')
  popup.onload = () => {
    const content = popup.document.querySelector('h1').innerText
    ipcRenderer.send('answer', content)
  }
</script>
</body>
</html>