I'm using mobiledoc-kit to create an editor. It comes with a few toolbar buttons that let you make text bold, italic, etc. Some text can be wrapped in H1, H2... tags.
What I want is to create a button that will wrap text in a custom tag with attributes (<div data-tag="some data here">TEXT</div>)
I can see the tags are limited in VALID_MARKUP_TAGNAMES constant which is in src/js/models/markup.js file
I installed mobiledoc-kit via npm.
The question is how can I extend this file and add a custom tag to the constant.