Discourse CommonMark text highlighting?

Probably not really a bug but, I know that “standard” Markdown discussions are somewhat fraught and this question seems to not be dealt with in the latest ComonMark spec but…

It appears that, in accordance with at least one (the Ghost project) guide of the CommonMark spec:


should give you a strikethrough (and it does) but


should give you a ==highlight== text - and it doesn’t.

Attempting to use <span style=“background-color:yellow;”> tags or other means seems to also not work for me…

So, based on the CommonMark used by Discourse, is there a way to do text highlighting? Is there a better guide for us to use to get answers to questions like this?


Ghost’s version of markdown is fully CommonMark compliant with a few other useful features like footnotes.

Highlight being of the “few other”.

<mark>Highlight</mark> being of the "few other".

You can try and package GitHub - markdown-it/markdown-it-mark: <mark> tag plugin for markdown-it markdown parser as a plugin using Developer's guide to Markdown extensions.


Interesting (but, beyond what I can do in the 2 weeks I have to put into this at this time)…

Playing on the Markdown-it demo page, exactly what I want is available. Off hand, do you know if:

  1. The version of Markdown-it included in Discourse is feature hobbled in some way?
  2. Markdown-it might be an older version in the Discourse release?

(I know that this is easily found out by me but you were so quick in responding before that I’m now a spoiled user dependent on you :grin:)

We use just markdown-it.

That demo also supports footnotes which are a markdown-it plugin, that we provide at Discourse footnote.


Good catch and clue…

On our test site, installed Discourse footnote plugin and footnotes work fine (settings are all turned on) but highlighting is still as before…

Thanks again for your suggestion…

Someone would have to re-package the highlight markdown-it plugin into a Discourse plugin for it to become available. You could likely take a stab at it by forking the footnote plugin and finding all instance of footnote and replacing it with “mark”


This caught my interest as I thought it would useful on my installation as well. So here is a plugin for highlighting. Being as it is my first plugin, I suspect it needs a fair bit of cleanup even with having used other plugins as templates/inspiration. It did work in my test environment though.



I added you to the @plugin_authors group so feel free to do a full post in #plugin about it!


We already have insert and delete

We already have <ins>insert</ins> and <del>delete</del>


Would love to use this @sirideain

I’m getting this?
"“Import Error: about.json does not exist, or is invalid. Are you sure this is a Discourse Theme”?

Thank you.

This is a plugin, not a theme. You’ll need to check Install Plugins in Discourse