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:
~~strikethrough~~
should give you a strikethrough (and it does) but
==highlight==
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?
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.