Add behaviour on Publish button, before publish post

Hi, I want to develop a really simple plugin. Just have to add some behaviour through javascript right after the user clicks on Publish button to display some info, and then go on publishing the post.

Is this possible? I’ve seen some of the docs, and saw publish_post filter, but I’m not sure if it applies. I’d be grateful for any piece of advice.

Thx,
itg