This is the documentation for version 2.3. Please consider upgrading your code to the latest stable version


The AttributesExtension allows HTML attributes to be added from within the document.

Attribute Syntax

The basic syntax was inspired by Kramdown’s Attribute Lists feature.

You can assign any attribute to a block-level element. Just directly prepend or follow the block with a block inline attribute list. That consists of a left curly brace, optionally followed by a colon, the attribute definitions and a right curly brace:

> A nice blockquote
{: title="Blockquote title"}

This results in the following output:

<blockquote title="Blockquote title">
<p>A nice blockquote</p>

CSS-selector-style declarations can be used to set the id and class attributes:

{#id .class}
## Header


<h2 class="class" id="id">Header</h2>

As with a block-level element you can assign any attribute to a span-level elements using a span inline attribute list, that has the same syntax and must immediately follow the span-level element:

This is *red*{style="color: red"}.


<p>This is <em style="color: red">red</em>.</p>


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 AttributesExtension:

use League\CommonMark\Environment\Environment;
use League\CommonMark\Extension\Attributes\AttributesExtension;
use League\CommonMark\Extension\CommonMark\CommonMarkCoreExtension;
use League\CommonMark\MarkdownConverter;

// Define your configuration, if needed
$config = [];

// Configure the Environment with all the CommonMark parsers/renderers
$environment = new Environment($config);
$environment->addExtension(new CommonMarkCoreExtension());

// Add this extension
$environment->addExtension(new AttributesExtension());

// Instantiate the converter engine and start converting some Markdown!
$converter = new MarkdownConverter($environment);
echo $converter->convert('# Hello World!');

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