How to apply class to every other post/small action?

[orangeandblack5]

@Johani has a great and very informative post that talks some about how to add classes posts via JavaScript:

How do I customise the styling of "solved topics" in the main list?

TL;DR This will add a topic-solution class to posts marked as the answer. api.addPostClassesCallback((attrs) => { if (attrs.accepted_answer) return ["topic-solution"]; }); The classes that a post has are determined here. The hook you want already exists at the very end of that… like so. The plugin-api has a method that allows you to add classes to a post based on a condition. What that does is that it applies a given callback and returns a class to be added if the condition is met…

However, from my testing it appears that small actions (excluding locks/unlocks/pins, which count as full posts) are excluded from this method. What would be the best way to accomplish the same thing, but also include small actions?

We would like to apply a class to every other post/small-action, so we need something that can select both of them rather than attempting to target them individually. For example, we’d like to be able to target the bolded lines in the following example:

Post
Post
Post
Small Action
Post
Post
Small Action
Post
Small Action
Post
Post

[orangeandblack5]

What is a topic participant and what are the odds this is what we’re looking for?

discourse/discourse/blob/main/app/assets/javascripts/discourse/app/lib/plugin-api.js#L919-L929

That makes it sound like it’s selecting a user but I’m honestly not sure.