JSFiddle - React, Tailwind, and code Playground

HTML

<span id="user">
My Name
</span>

<iframe id="my-iframe" height=200 width=300>
</iframe>

JavaScript

var iframe = $("#my-iframe")[0].contentWindow.document;

$("body", iframe).html("<input type=\"button\" id=\"myButton\" value=\"click\">");

$("#myButton", iframe).click(function(){
var userName = $("#user").text();
alert(userName);
});