league/commonmark
Extensible PHP Markdown parser supporting the full CommonMark spec and GitHub-Flavored Markdown. Works with PHP 7.4+ (mbstring) and provides simple converters to turn Markdown into HTML with configurable safety options.
layout: default title: Default Attributes Extension description: The DefaultAttributesExtension allows you to apply default HTML classes and other attributes using configuration options. redirect_from:
The DefaultAttributesExtension allows you to apply default HTML classes and other attributes using configuration options.
It works by applying the attributes to the nodes during the DocumentParsedEvent event - right after the nodes are parsed but before they are rendered.
(As a result, it's possible that renderers may add other attributes - the goal of this extension is only to provide custom defaults.)
This extension is bundled with league/commonmark. This library can be installed via Composer:
composer require league/commonmark
See the installation section for more details.
Configure your Environment as usual and simply add the DefaultAttributesExtension:
use League\CommonMark\Environment\Environment;
use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
use League\CommonMark\Extension\CommonMark\Node\Block\Heading;
use League\CommonMark\Extension\CommonMark\Node\Inline\Link;
use League\CommonMark\Extension\DefaultAttributes\DefaultAttributesExtension;
use League\CommonMark\Extension\Table\Table;
use League\CommonMark\MarkdownConverter;
use League\CommonMark\Node\Block\Paragraph;
// Define your configuration, if needed
// Extension defaults are shown below
// If you're happy with the defaults, feel free to remove them from this array
$config = [
'default_attributes' => [
Heading::class => [
'class' => static function (Heading $node) {
if ($node->getLevel() === 1) {
return 'title-main';
} else {
return null;
}
},
],
Table::class => [
'class' => 'table',
],
Paragraph::class => [
'class' => ['text-center', 'font-comic-sans'],
],
Link::class => [
'class' => 'btn btn-link',
'target' => '_blank',
],
],
];
// Configure the Environment with all the CommonMark parsers/renderers
$environment = new Environment($config);
$environment->addExtension(new CommonMarkCoreExtension());
// Add the extension
$environment->addExtension(new DefaultAttributesExtension());
// Instantiate the converter engine and start converting some Markdown!
$converter = new MarkdownConverter($environment);
echo $converter->convert('# Hello World!');
This extension can be configured by providing a default_attributes array. Each key in the array should be a FQCN for the node class you wish to apply the default attribute to, and the values should be a map of attribute names to attribute values.
Attribute values may be any of the following types:
stringstring[]boolcallable (parameter is the Node, return value may be string|string[]|bool)Here's an example that will apply Bootstrap 4 classes and attributes:
$config = [
'default_attributes' => [
Table::class => [
'class' => ['table', 'table-responsive'],
],
BlockQuote::class => [
'class' => 'blockquote',
],
],
];
Here's a more complex example that uses a callable to add a class only if the paragraph immediately follows an <h1> heading:
$config = [
'default_attributes' => [
Paragraph::class => [
'class' => static function (Paragraph $paragraph) {
if ($paragraph->previous() instanceof Heading && $paragraph->previous()->getLevel() === 1) {
return 'lead';
}
return null;
},
],
],
];
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