Manually dispatchEvent DOMContentLoaded

This works for me in Firefox:

var DOMContentLoaded_event = document.createEvent("Event")
DOMContentLoaded_event.initEvent("DOMContentLoaded", true, true)
window.document.dispatchEvent(DOMContentLoaded_event)

Since initEvent is deprecated here, it's better to use Event constructor like this:

window.document.dispatchEvent(new Event("DOMContentLoaded", {
  bubbles: true,
  cancelable: true
}));