I created an iframe with content dynamically loaded with jquery like this and I want the iframe document to access its content as soon as it has been loaded:
jQuery('<iframe>', {
    id: 'widgetFrm',
    width: '100%'
})
.appendTo('#widgetDiv')
.on('load', function () {
    jQuery(this).contents().find('body').append(data.html);
})
The frame document knows about jquery because I use
if (typeof(jQuery) == "undefined") {
    var iframeBody = document.getElementsByTagName("body")[0];
    var jQuery = function (selector) { return parent.jQuery(selector, iframeBody);
}
there. Within the iframe, I'd like to access its div elements after everything got loaded, I'm using jQuery(document).ready for that (within the dynamically loaded content). 
Problem: Accessing its own elements in the frame document somehow does not work with jquery 1.x in document ready block!
document.getElementById('#someDiv') returns null and jQuery('#someDiv').prop('scrollHeight') returns undefined, although the frame content has that element (accessing it when clicking a button works!). With newer jQuery versions (for instance 3.3.1) it works, but I can't change that version currently. Is there another way to do that?
Thank you!