JSFiddle - React, Tailwind, and code Playground

HTML

<div class="gallery front" style="opacity: 1; ">
    <span class="image-wrapper current" style="opacity: 1; ">
        <a class="advance-link" rel="history" href="#1" title="Title #10">
            <img alt="Title #10" src="http://dev3.dhut.ch/img/10.jpeg">
        </a>
    </span>
</div>

CSS

.test {
    width:200px;
    height:200px;
    opacity:.5;
}

JavaScript

$('.advance-link>img').addClass('test');