Markdown in HTML¶

Summary¶

An extension that parses Markdown inside of HTML tags.

Syntax¶

By default, Markdown ignores any content within a raw HTML block-level element. With the md-in-html extension enabled, the content of a raw HTML block-level element can be parsed as Markdown by including a markdown attribute on the opening tag. The markdown attribute will be stripped from the output, while all other attributes will be preserved.

The markdown attribute can be assigned one of three values: "1", "block", or "span".

markdown="1"¶

When the markdown attribute is set to "1", then the parser will use the default behavior for that specific tag.

The following tags have the block behavior by default: article, aside, blockquote, body, colgroup, details, div, dl, fieldset, figcaption, figure, footer, form, group, header, hgroup, hr, iframe, main, map, menu, nav, noscript, object, ol, output, progress, section, table, tbody, tfoot, thead, tr, ul and video.

For example, the following:

<div markdown="1">
This is a *Markdown* Paragraph.
</div>

… is rendered as:

<div>
<p>This is a <em>Markdown</em> Paragraph.</p>
</div>

The following tags have the span behavior by default: address, dd, dt, h[1-6], legend, li, p, td, and th.

For example, the following:

<p markdown="1">
This is not a *Markdown* Paragraph.
</p>

… is rendered as:

<p>
This is not a <em>Markdown</em> Paragraph.
</p>

markdown="block"¶

When the markdown attribute is set to "block", then the parser will force the block behavior on the contents of the element so long as it is one of the block or span tags.

The content of a block element is parsed into block-level content. In other words, the text is rendered as paragraphs, headers, lists, blockquotes, etc. Any inline syntax within those elements is processed as well.

For example, the following:

<section markdown="block">
# A header.

A *Markdown* paragraph.

* A list item.
* A second list item.

</section>

… is rendered as:

<section>
<h1>A header.</h1>
<p>A <em>Markdown</em> paragraph.</p>
<ul>
<li>A list item.</li>
<li>A second list item.</li>
</ul>
</section>

markdown="span"¶

When the markdown attribute is set to "span", then the parser will force the span behavior on the contents of the element so long as it is one of the block or span tags.

The content of a span element is not parsed into block-level content. In other words, the content will not be rendered as paragraphs, headers, etc. Only inline syntax will be rendered, such as links, strong, emphasis, etc.

For example, the following:

<div markdown="span">
# *Not* a header
</div>

… is rendered as:

<div>
# <em>Not</em> a header
</div>

Ignored Elements¶

The following tags are always ignored, regardless of any markdown attribute: canvas, math, option, pre, script, style, and textarea. All other raw HTML tags are treated as span-level tags and are not affected by this extension.

Nesting¶

When nesting multiple levels of raw HTML elements, a markdown attribute must be defined for each block-level element. For any block-level element which does not have a markdown attribute, everything inside that element is ignored, including child elements with markdown attributes.

For example, the following:

<article id="my-article" markdown="1">
# Article Title

A Markdown paragraph.

<section id="section-1" markdown="1">
## Section 1 Title

<p>Custom raw **HTML** which gets ignored.</p>

</section>

<section id="section-2" markdown="1">
## Section 2 Title

<p markdown="1">**Markdown** content.</p>

</section>

</article>

… is rendered as:

<article id="my-article">
<h1>Article Title</h1>
<p>A Markdown paragraph.</p>
<section id="section-1">
<h2>Section 1 Title</h2>
<p>Custom raw **HTML** which gets ignored.</p>
</section>
<section id="section-2">
<h2>Section 2 Title</h2>
<p><strong>Markdown</strong> content.</p>
</section>
</article>

When the value of an element’s markdown attribute is more permissive that its parent, then the parent’s stricter behavior is enforced. For example, a block element nested within a span element will be parsed using the span behavior. However, if the value of an element’s markdown attribute is the same as, or more restrictive than, its parent, the the child element’s behavior is observed. For example, a block element may contain either block elements or span elements as children and each element will be parsed using the specified behavior.

Tag Normalization¶

While the default behavior is for Markdown to not alter raw HTML, as this extension is parsing the content of raw HTML elements, it will do some normalization of the tags of block-level elements. For example, the following raw HTML:

<div markdown="1">
<p markdown="1">A Markdown paragraph with *no* closing tag.
<p>A raw paragraph with *no* closing tag.
</div>

… is rendered as:

<div>
<p>A Markdown paragraph with <em>no</em> closing tag.
</p>
<p>A raw paragraph with *no* closing tag.
</p>
</div>

Notice that the parser properly recognizes that an unclosed <p> tag ends when another <p> tag begins or when the parent element ends. In both cases, a closing </p> was added to the end of the element, regardless of whether a markdown attribute was assigned to the element.

To avoid any normalization, an element must not be a descendant of any block-level element which has a markdown attribute defined.

Usage¶

From the Python interpreter:

>>> import markdown
>>> html = markdown.markdown(text, extensions=['md_in_html'])