JSFiddle - React, Tailwind, and code Playground

HTML

<div class="hello">Hello World!</div>

CSS

.flash {
    background-color: yellow;
    display: none;
    position: absolute;
    width: 100%;
    height: 100%;
}

JavaScript

var flash = "<div class='flash'></div>";
$(".hello").prepend(flash);
// $(flash).show().fadeOut(); # strange, it won't unhide when you create the JQuery object directly
$('.flash').show().fadeOut('slow');