This is the documentation for the unsupported version 1.0. Please consider upgrading your code to the latest stable version

Block Rendering

Block renderers are responsible for converting the parsed AST elements into their HTML representation.

All block renderers should implement BlockRendererInterface and its render() method:


public function render(AbstractBlock $block, ElementRendererInterface $htmlRenderer, bool $inTightList = false);

The HtmlRenderer will call this method whenever a supported block element is encountered in the AST being rendered.

If the method can only handle certain block types, be sure to verify that you’ve been passed the correct type.


Return value

The method must return the final HTML representation of the block and any of its contents. This can be an HtmlElement object (preferred; castable to a string), a string of raw HTML, or null if it could not render (and perhaps another renderer should give it a try).

If you choose to return an HTML string you are responsible for handling any escaping that may be necessary.


Instead of manually building the HTML output yourself, you can leverage the HtmlElement to generate that for you. For example:

use League\CommonMark\HtmlElement;

$link = new HtmlElement('a', ['href' => ''], 'GitHub');
$img = new HtmlElement('img', ['src' => 'logo.jpg'], '', true);

Designating Block Renderers

When registering your renderer, you must tell the Environment which block element class your renderer should handle. For example:

use League\CommonMark\Block\Element\FencedCode;
use League\CommonMark\Environment;

$environment = Environment::createCommonMarkEnvironment();

// First param - the block class type that should use our renderer
// Second param - instance of the block renderer
$environment->addBlockRenderer(FencedCode::class, new MyCustomCodeRenderer());

A single renderer could even be used for multiple block types:

use League\CommonMark\Block\Element\FencedCode;
use League\CommonMark\Block\Element\IndentedCode;
use League\CommonMark\Environment;

$environment = Environment::createCommonMarkEnvironment();

$myRenderer = new MyCustomCodeRenderer();

$environment->addBlockRenderer(FencedCode::class, $myRenderer, 10);
$environment->addBlockRenderer(IndentedCode::class, $myRenderer, 20);

Multiple renderers can be added per element type - when this happens, we use the result from the highest-priority renderer that returns a non-null result.


Here’s a custom renderer which renders thematic breaks as text (instead of <hr>):

use League\CommonMark\Environment;
use League\CommonMark\Node\Block\AbstractBlock;
use League\CommonMark\Renderer\Block\BlockRendererInterface;
use League\CommonMark\Renderer\NodeRendererInterface;
use League\CommonMark\Util\HtmlElement;

class TextDividerRenderer implements BlockRendererInterface
    public function render(AbstractBlock $block, NodeRendererInterface $htmlRenderer, bool $inTightList = false)
        return new HtmlElement('pre', ['class' => 'divider'], '==============================');

$environment = Environment::createCommonMarkEnvironment();
$environment->addBlockRenderer('League\CommonMark\Block\Element\ThematicBreak', new TextDividerRenderer());


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