JSFiddle - React, Tailwind, and code Playground

HTML

<div id="body">
    <a id="lien" href="http://forum.alsacreations.com/topic-4-74070-1.html">Mon lien</a>
    
</div>

CSS

#body {
    background: red;
    width: 100%;
    height: 300px;
}
#body.body-img {
    background: url(http://cdn.alsacreations.net/css/img/logo-alsacreations-com-2014.png);
}

JavaScript

document.getElementById("lien").addEventListener("mouseover", function( event ) {   
    document.getElementById("body").classList.add("body-img");
  }, false);

 document.getElementById("lien").addEventListener("mouseleave", function( event ) {   
    document.getElementById("body").classList.remove("body-img");
  }, false);