JSFiddle - React, Tailwind, and code Playground

HTML

<div id="all">
<img src="http://p1.pichost.me/i/19/1422518.jpg" alt="Smiley face" height="420" width="420">
</div>


<div id="loading">LOADING</div>

CSS

#all{
	display: none;
}
#loading {
position:absolute;
 top: 45%;
 left: 50%;
 -webkit-transform: translate(-50%, -50%);
 transform: translate(-50%, -50%);
    z-index: 100;
    width: 100px;
    height: 100px;
}

JavaScript

function onReady(callback) {
    var intervalID = window.setInterval(checkReady, 1000);

    function checkReady() {
        if (document.getElementsByTagName('body')[0] !== undefined) {
            window.clearInterval(intervalID);
            callback.call(this);
        }
    }
}

function show(id, value) {
    document.getElementById(id).style.display = value ? 'block' : 'none';
}

onReady(function () {
    show('all', true);
    show('loading', false);
});