Asterisk | Technology Tales

Rendering Markdown in WordPress without plugins by using Parsedown

4^th November 2025

Much of what is generated using GenAI as articles is output as Markdown, meaning that you need to convert the content when using it in a WordPress website. Naturally, this kind of thing should be done with care to ensure that you are the creator and that it is not all the work of a machine; orchestration is fine, regurgitation does that add that much. Naturally, fact checking is another need as well.

Writing plain Markdown has secured its own following as well, with WordPress plugins switching over the editor to facilitate such a mode of editing. When I tried Markup Markdown, I found it restrictive when it came to working with images within the text, and it needed a workaround for getting links to open in new browser tabs as well. Thus, I got rid of it to realise that it had not converted any Markdown as I expected, only to provide rendering at post or page display time. Rather than attempting to update the affected text, I decided to see if another solution could be found.

This took me to Parsedown, which proved to be handy for accomplishing what I needed once I had everything set in place. First, that meant cloning its GitHub repo onto the web server. Next, I created a directory called includes under that of my theme. Into there, I copied Parsedown.php to that location. When all was done, I ensured that file and directory ownership were assigned to www-data to avoid execution issues.

Then, I could set to updating the functions.php file. The first line to get added there included the parser file:

require_once get_template_directory() . '/includes/Parsedown.php';

After that, I found that I needed to disable the WordPress rendering machinery because that got in the way of Markdown rendering:

remove_filter('the_content', 'wpautop'); remove_filter('the_content', 'wptexturize');

The last step was to add a filter that parsed the Markdown and passed its output to WordPress rendering to do the rest as usual. This was a simple affair until I needed to deal with code snippets in pre and code tags. Hopefully, the included comments tell you much of what is happening. A possible exception is $matches[0]which itself is an array of entire <pre>...</pre> blocks including the containing tags, with $i => $block doing a $key (not the same variable as in the code, by the way) => $value lookup of the values in the array nesting.

add_filter('the_content', function($content) {
    // Prepare a store for placeholders
    $placeholders = [];

    // 1. Extract pre blocks (including nested code) and replace with safe placeholders
    preg_match_all('//si', $content, $pre_matches);
    foreach ($pre_matches[0] as $i => $block) {
        $key = "§PREBLOCK{$i}§";
        $placeholders[$key] = $block;
        $content = str_replace($block, $key, $content);
    }

    // 2. Extract standalone code blocks (not inside pre)
    preg_match_all('/).*?<\/code>/si', $content, $code_matches);
    foreach ($code_matches[0] as $i => $block) {
        $key = "§CODEBLOCK{$i}§";
        $placeholders[$key] = $block;
        $content = str_replace($block, $key, $content);
    }

    // 3. Run Parsedown on the remaining content
    $Parsedown = new Parsedown();
    $content = $Parsedown->text($content);

    // 4. Restore both pre and code placeholders
    foreach ($placeholders as $key => $block) {
        $content = str_replace($key, $block, $content);
    }

    // 5. Apply paragraph formatting
    return wpautop($content);
}, 12);

All of this avoided dealing with extra plugins to produce the required result. Handily, I still use the Classic Editor, which makes this work a lot more easily. There still is a Markdown import plugin that I am tempted to remove as well to streamline things. That can wait, though. It best not add any more of them any way, not least avoid clashes between them and what is now in the theme.

Displaying superscripted text in Hugo website content

6^th January 2025

In a previous post, there was a discussion about displaying ordinal publishing dates with superscripted suffixes in Hugo and WordPress. Here, I go further with inserting superscripted text into Markdown content. Because of the default set up for the Goldmark Markdown renderer, it is not as simple as adding <sup>...</sup> constructs to your Markdown source file. That will generate a warning like this:

WARN Raw HTML omitted while rendering "[initial location of Markdown file]"; see https://gohugo.io/getting-started/configuration-markup/#rendererunsafe You can suppress this warning by adding the following to your site configuration: ignoreLogs = ['warning-goldmark-raw-html']

Because JavaScript can be added using HTML tags, there is an added security hazard that could be overlooked if you switch off the warning as suggested. Also, Goldmark does not interpret Markdown specifications of superscripting without an extension whose incorporation needs some familiarity with Go development.

That leaves using a Shortcode. These go into layouts/shortcodes under your theme area; the file containing mine got called super.html. The content is the following one-liner:

<sup>{{ .Get 0 | markdownify }}⁢/sup>

This then is what is added to the Markdown content:

{{< super "th" >}}

What happens here is that the Shortcode picks up the content within the content within the quotes and encapsulates it with the HTML superscript tags to give the required result. This approach can be extended for subscripts and other similar ways of rendering text, too. All that is required is a use case, and the rest can be put in place.