electron/spec/fixtures/module/preload-pdf-loaded-in-subframe.js

const { ipcRenderer } = require('electron');

document.addEventListener('DOMContentLoaded', (event) => {
  const subframe = document.querySelector('#pdf-frame');
  if (subframe) {
    subframe.contentWindow.addEventListener('pdf-loaded', (event) => {
      ipcRenderer.send('pdf-loaded', event.detail);
    });
  }
});