How can I get all the other JSX elements and their props inside an editor?

[detarkende]

I'm creating my own JSX heading component which can have a slug (the slug will be the id of the renderes <h2>, so you can simply link to a title on the page).

I'd like to make sure that all slugs are unique on the page, but for that I need to get all the mdastNodes, then filter them to find all the other headings currently in the editor.