How do I add a class to all links?

[ctessmer]

What I want

I'd like to add a class to all my links. For instance, I'd like to convert this:

Markdown

What has [myspace](https://myspace.com) become?!

To this:

HTML

What has <a href="https://myspace.com" class="link">myspace</a> become?!

Why I want it

I use tailwindcss and have some nice components setup—one being a link component. I'd like to attach that to every link in the rendered html so I don't have to duplicate the component in css.

Tailwindcss component

.link {
     @apply underline decoration-2 text-blue-600 hover:text-blue-800 dark:text-blue-400 font-semibold;
}

What I tried

It looks like there's something perhaps built-in to do this at the end of the Abstract Syntax Tree section:

HTML Attributes

use League\CommonMark\Extension\CommonMark\Node\Inline\Link;

$link = new Link('https://twitter.com/colinodell', '@colinodell');
$link->data->append('attributes/class', 'social-link');
$link->data->append('attributes/class', 'twitter');
$link->data->set('attributes/target', '_blank');
$link->data->set('attributes/rel', 'noopener');

But I'm unsure how to…

1. Integrate the above HTML Attributes example into my code (just to get a proof of concept).
2. Adapt it so it targets all links—not just text that says @colinodell.
3. Register into my converter (not sure if register is the right word).

My existing, working conversion code

# Use markdown converter library
use League\CommonMark\Environment\Environment;
use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
use League\CommonMark\Extension\SmartPunct\SmartPunctExtension;
use League\CommonMark\Extension\Strikethrough\StrikethroughExtension;
use League\CommonMark\Extension\FrontMatter\FrontMatterExtension;
use League\CommonMark\Extension\FrontMatter\Output\RenderedContentWithFrontMatter;
use League\CommonMark\MarkdownConverter;

# Define markdown converter environment
$environment = new Environment();
$environment->addExtension(new CommonMarkCoreExtension());
$environment->addExtension(new SmartPunctExtension());
$environment->addExtension(new StrikethroughExtension());
$environment->addExtension(new FrontMatterExtension());

# Define converter
$converter = new MarkdownConverter($environment);

Can you tell me how to solve this?

PS: Thanks so much for the incredible library. It still blows me away that I can use it (and others' libraries) for free.

[colinodell]

The Default Attributes extension does exactly this - no custom code required!

If you really did want to implement this with custom code, here's an example you could easily adapt - just change this part:

     public function onDocumentParsed(DocumentParsedEvent $event): void
     {
         $document = $event->getDocument();
         $walker = $document->walker();
         while ($event = $walker->next()) {
             $node = $event->getNode();
 
             // Only stop at Link nodes when we first encounter them
             if (!($node instanceof Link) || !$event->isEntering()) {
                 continue;
             }

-            $url = $node->getUrl();
-            if ($this->isUrlExternal($url)) {
-                $node->data->append('attributes/class', 'external-link');
-            }
+            $link->data->append('attributes/class', 'link');
         }
     }

But since that extension should do everything you need I'd recommend just using that :)

PS: Thanks so much for the incredible library. It still blows me away that I can use it (and others' libraries) for free.

Thank you so much for those kind words!

[ctessmer]

The Default Attributes extension does exactly this - no custom code required!

Perfect! Thank you so much for letting me know. Exactly what I was looking for. (And I thank you for going the extra mile and showing me how to do it in a totally custom way!)

And btw I tried it, and it almost works like a charm—but I may have discovered a bug (one that I can easily work around). But just so you know:

Bug overview

The library throws a fatal error and exits if the value of the class is link.

How to duplicate

1. Set config:

$config = [
	'default_attributes' => [
		Link::class => [
			'class' => 'link',
			'target' => '_self',
		],
	],
];

2. Supply library with a link in markdown:

Markdown

What has [myspace](https://myspace.com) become?!

3. Execute code.

Expected result

HTML

<p>What has <a href="https://myspace.com" class="link">myspace</a> become?!</p>

Actual result

Fatal error: Uncaught ArgumentCountError: link() expects exactly 2 arguments, 1 given…