JSFiddle - React, Tailwind, and code Playground

HTML

<div class="a">A</div>
<div class="b">B</div>
<div class="c">C</div>
<div id="d">D</div>

CSS

div{
    padding:10px;
    border:1ps black;
}

JavaScript

var obj = {
    '.a': 'content a',
    '.b': 'content b',
    '.c': 'content c'
};

var selector = Object.keys(obj).join(',');
$(selector).mouseover(function() {
    $('#d').html(obj['.' + this.className]);
});