JSFiddle - React, Tailwind, and code Playground

HTML

<div id="body"></div>
<input id="button" type="button" value="Submit iframe"/>

CSS

iframe {
    height: 300px;
    width : 100%;
}

JavaScript

var iframe = $("<iframe></iframe>").appendTo("#body")[0];
var doc = iframe.document;
var content = '<form method="get"><input name="hidden" type="hidden" value="123"/></form>';
doc = iframe.contentDocument;
doc.writeln(content);
doc.close();

$('input#button').click(function () {
	$('iframe').contents().find('form')[0].submit();
});