OnLoad event is limiting the app

[gustavopi]

Hi! I am trying to include this widget in my site. However, it will auto launch by the onload function at the end, means all must be already loaded in the document.

document.body.onload = function () {
    var chatSelector = document.querySelectorAll(SELECTOR_CHAT_WIDGET);

    for (var i = 0; i < chatSelector.length; i++) {
      var element = chatSelector[i];
      var data = new Chat(element, {}, []); // eslint-disable-line no-unused-vars
    }
  };

But in many cases the html loaded is just the skeleton, there is a lot to loaded yet. In my case, I wish to put the toggle button in the "Search" menu that is loaded after, so the class won't find the button.
Is there a way to avoid this limitation?