Log the load events of a document.

dom_load_events.js

const domContentLoadedPromise = new Promise(resolve => {
  window.addEventListener("DOMContentLoaded", () => {
    dump(">>> dialog - DOMContentLoaded event" + window.document.documentURI + "\n");
    resolve();
  }, { capture: true, once: true });
});

domContentLoadedPromise.then(() => {
  dump(">>> dialog - Promise for domContentLoadedPromise resolved\n");
});

window.addEventListener("load", () => {
  dump(">>> dialog - load event\n")
});