MediaArt

This plugin provides shortcodes to show/hide content with an optional accordion behavior:
<ul>
<li>New shortcode: <code>[ma_collapse]...[/ma_collapse]</code> (and <code>ma_collapse_level2..7</code>)</li>
<li>Legacy compatibility: Keeps legacy <code>bg_collapse*</code> shortcodes functional (where possible without breaking other installed plugins).</li>
</ul>
The plugin is written to follow WordPress.org best practices: 
* No inline JavaScript in PHP templates 
* Admin actions protected by capability checks and nonces 
* Sanitization/escaping on output 
* Translatable strings (EN as base; Czech translation included)
<h3>Usage</h3>
Basic: 
 [ma_collapse]Hidden content[/ma_collapse]
With custom label: 
 [ma_collapse more=”Show more” less=”Show less”]Hidden content[/ma_collapse]
Accordion grouping: 
Use the same <code>group</code> attribute on multiple shortcodes. 
 [ma_collapse group=”faq”]Item 1[/ma_collapse] [ma_collapse group=”faq”]Item 2[/ma_collapse]
Legacy: 
 [bg_collapse]Hidden content[/bg_collapse]

Show Hide Accordion by MediaArt

Create collapse/expand sections and accordions via shortcodes (ma_collapse + legacy bg_collapse).

Robert Noakes

Adds functionality to collapse and expand nav menus within the WordPress admin. All parent nav menu items are collapsed by default, but you have the option to store the collapsed/expanded state for the menus on a user-by-user basis.
<a href="https://noakesplugins.com/kb/nav-menu-collapse/" rel="nofollow ugc">View the Knowledge Base »</a>

Nav Menu Collapse

Simple, to the point, this should absolutely be in core.

Adds functionality to collapse and expand nav menus within the WordPress admin.

Show Hide Accordion by MediaArt vs Nav Menu Collapse