Issue

As explained in the manual, you can use shown attributes within <option> tags since this PR: #18998
This works for com_config if you try, but it does not (always) work for other components.

Steps to reproduce the issue

• This does not work, when used with a 'new' component (or e.g. with com_banners for this example), when you follow the directions of the mentioned manual. This is because /media/system/js/showon.min.js is not automatically loaded. I think there's either a bug, or the manual is missing this info.
• Check Chrome DevTools > Sources > your/site/media/system/js, which should show showon.min.js.
  It's visible at https://website/administrator/index.php?option=com_config. But if you go to https://website/administrator/index.php?option=com_banners&view=banner&layout=edit you'll see showon.min.js is missing.

Steps to fix the issue

Either update the manual or the Joomla code. I don't know what's preferred.
If you'll manually add the following to your existing component's joomla.asset.json:

{
	"name": "showon",
	"type": "script",
	"dependencies": [
		"core",
		"showon.es5"
	],
	"uri": "system/showon.min.js",
	"attributes": {
		"type": "module"
	},
	"version": "bfc733e48a923aaffb3d959cd04f176bad7d7d52"
}

And load this script with the web asset manager:

$wa = $this->document->getWebAssetManager();
$wa->useScript('showon');

Then it should work as expected.

Attention

It's key for this bug report to try the shown feature within an <option> tag, because it does always work within a <field> tag.

System information

Joomla! 4.1.0 Stable