<html>
<body>
<script type="text/javascript" charset="utf-8">
const {ipcRenderer} = window.top != null ? window.top.require('electron') : require('electron')
const popup = window.open()
popup.document.write('<h1>Hello</h1>')
const content = popup.document.querySelector('h1').innerText
ipcRenderer.send('answer', content)
</script>
</body>
</html>