JSFiddle - React, Tailwind, and code Playground

HTML

<a href="" data-info="text"><img src="http://yandex.st/morda-logo/i/logo.svg" alt=""></a>

CSS

a{
    position: relative;
    display: inline-block;
}

a:after{
    content: attr(data-info);
    position: absolute;
    top: 50%;
    left: 0;
    right: 0;
    color: blue;
    margin-top: -10px;
    font-size: 20px;
    text-align: center;
    z-index: 1;
}

JavaScript

document.getElementsByTagName("a")[0].onmouseover = function(){
  this.setAttribute("data-info", "qwe");  
};