JSFiddle - React, Tailwind, and code Playground

HTML

<iframe onload="alert('Loaded!');" id="page" src="https://essayvikings.com/" style="border:none; overflow:hidden; width:500px; height:300px;" allowTransparency="true" ></iframe>
<div id="a"></div>

JavaScript

if ($("#page").contents().find(".searchheader").text() == "") 
    {
        $("#a").text("Не загрузилось", $("#page").contents().find(".searchheader").text());
    }
else {
    $("#a").text("Загрузилось");
    alert ($("#page").contents().find(".searchheader").text());
    }