JSFiddle - React, Tailwind, and code Playground

HTML

<li>
    <img src="http://mlb-s2-p.mlstatic.com/adesivo-parede-infantil-mickey-donald-pateta-disney-baby-16663-MLB20124000600_072014-F.jpg"/>    
</li>
<li class="hoverDiv">
    <img src="http://mlb-s2-p.mlstatic.com/adesivo-parede-infantil-mickey-donald-pateta-disney-baby-16663-MLB20124000600_072014-F.jpg"/>    
</li>

CSS

li {
    position: relative;
    list-style:none;
    display:inline-block;
    margin: 10px;
}

li img {
    height:100px;
    width:100px;
}

div.loading {
    position: absolute;
    top:0;
    left:0;
    background: url('http://www.arabianbusiness.com/skins/ab.main/gfx/loading_spinner.gif') no-repeat center center;
    height:100px;
    width:100px;
}

JavaScript

$('li').on('mouseenter', function(){
    $(this).append('<div class="loading"></div>');
});

$('li').on('mouseleave', function(){
    $(this).find('div.loading').remove();
});