Justin Tadlock

<p>The Sliding Panel plugin creates a new sidebar for your site that allows you to add widgets.  These widgets appear within a responsive sliding panel at the top of your site on the front end.</p>
<h3>Features</h3>
<ul>
<li>It’s a jQuery-powered sliding panel.  That’s a feature in-and-of itself, right?</li>
<li>Uses widgets, so you can add pretty much anything you can add to any other sidebar.</li>
<li>Uses the WordPress-packaged jQuery.</li>
<li>Will automatically display with any correctly-coded theme.</li>
<li>Supports HTML5 and Schema.org microdata.</li>
<li>It’s responsive, so it’ll look good on any device.</li>
</ul>
<h3>Professional Support</h3>
<p>If you need professional plugin support from me, the plugin author, you can access the support forums at <a href="http://themehybrid.com/support" rel="nofollow ugc">Theme Hybrid</a>, which is a professional WordPress help/support site where I handle support for all my plugins and themes for a community of 40,000+ users (and growing).</p>
<h3>Plugin Development</h3>
<p>If you’re a theme author, plugin author, or just a code hobbyist, you can follow the development of this plugin on it’s <a href="https://github.com/justintadlock/sliding-panel" rel="nofollow ugc">GitHub repository</a>.</p>
<h3>Donations</h3>
<p>Yes, I do accept donations.  If you want to buy me a beer or whatever, you can do so from my <a href="http://themehybrid.com/donate" rel="nofollow ugc">donations page</a>.  I appreciate all donations, no matter the size.  Further development of this plugin is not contingent on donations, but they are always a nice incentive.</p>


Sliding Panel

Adds a responsive sliding panel to the top of your WordPress-powered site.

Miguel Useche

<p>This plugin provides a widget and a filter to display a collapsible list of categories in your sidebar or posts by using vanilla Javascript.</p>
<h4>Features</h4>
<ol>
<li>Support for Gutenberg blocks. Add it to any FSE theme or Gutenberg compatible theme.</li>
<li>Display a collapsed list of your archives to reduce space.</li>
<li>Uses vanilla JS to add effects and to be compatible with all browsers.</li>
<li>Select the symbol for expanding/collapsing categories</li>
<li>Select categories to exclude, so it shows only the categories you want.</li>
<li>Autoexpand selected category (including it parent or child).</li>
<li>Support for multiple instances.</li>
<li>Simple layout configuration</li>
<li>Shortcode support  <em>[JsCategoriesList]</em></li>
<li>Translated to Spanish, Italian Russian, Slovak, Czech.</li>
<li>Compatible with most JS cache and minify plugins.</li>
<li>And more to come…</li>
</ol>
<h3>Configuration</h3>
<ul>
<li>Title: title of the widget.</li>
<li>Trigger Symbol:  characters to be displayed as a bullet.</li>
<li>Symbol position: where to put the expand/collapse symbol.</li>
<li>Effect: JS’s effect to use.</li>
<li>Order by: display order of categories.</li>
<li>Expand: if list should be expanded or callapsed by default.</li>
<li>Show number of posts: display how many post are published in the category.</li>
<li>Show empty categories: display categories with no posts.</li>
<li>Open links in a new page: render category links with target=”_blank”.</li>
<li>Categories to include: categories to be included from the list.</li>
<li>Categories to exclude: categories to be excluded from the list.</li>
</ul>


JS Categories List Widget

Haven't seen any problems running this with WordPress 4.9.8, even though it's marked as untested for a long time.  It must have been well written.

Works well with 4.9.8

A simple Gutenberg block and JS widget (can be called from posts) for displaying categories in a list with some effects.

Sliding Panel vs JS Categories List Widget