JSFiddle - React, Tailwind, and code Playground

HTML

<div id="preloader"></div>
<iframe src="https:www.tcsion.com/" id="foo"></iframe>

CSS

#preloader {
    position: fixed;
    left: 0;
    top: 0;
    z-index: 999;
    width: 100%;
    height: 100%;
    overflow: visible;
    background: #333 url('//cdnjs.cloudflare.com/ajax/libs/file-uploader/3.7.0/processing.gif') no-repeat center center;
}

JavaScript

jQuery(document).ready(function ($) {
    $("#foo").load(function () {
       
            $('#preloader').fadeOut('fast', function () {
          
        });

    });  
});