JSFiddle - React, Tailwind, and code Playground

HTML

<form id="myform" action="http://fiddle.jshell.net/" target="myiframe">
     //some fields
</form>

<iframe id="myiframe" name="myiframe" src=""></iframe>

CSS

#myiframe {
    border: 1px solid red;
    display: block;
    width: 100%;
}

JavaScript

var iFrame = document.getElementById("myiframe");
var form = document.getElementById("myform");

iFrame.onload = function () {
    /** do smth with your iframe data */
    console.log(iFrame.contentDocument.body.innerHTML);
};

form.submit();