JSFiddle - React, Tailwind, and code Playground

HTML

<li class="post" style="width: 621px;">
    <div class="mediaholder">
        <div class="mediaholder_innerwrap overlay cap-icon enlarge">
		<a href="#" class="view" data-rel="lightbox" rel="lightbox">
			<img width="440" height="330" src="#" class="attachment-portfolio-index wp-post-image">
		</a>
	    </div>
    </div>
    <div class="detailholder">
        <h4 class="post-title"><a href="#">Example Title One</a></h4>
        </div>
    </div>
</li>
<li class="post" style="width: 621px;">
    <div class="mediaholder">
        <div class="mediaholder_innerwrap overlay cap-icon enlarge">
		<a href="#" class="view" data-rel="lightbox" rel="lightbox">
			<img width="440" height="330" src="#" class="attachment-portfolio-index wp-post-image">
		</a>
	</div>
    </div>
    <div class="detailholder">
        <h4 class="post-title"><a href="#">Example Title Two</a></h4>
        </div>
    </div>
</li>

JavaScript

jQuery(document).ready(function ($) {
        $('.post-title').each(function () {
            $(this).parents('li').children('.mediaholder').append(this);
        });
    });