Hey Sam - I’ve been playing with this quite a lot today. It looks great! I do think there’s still quite a lot to do, though. Some of it, I can definitely help with. Some of it is possibly beyond my capacity, particularly with my university starting back up.
Anyways, here are a few of my thoughts.
Zoom
Zoom on hover is no longer available in MathJax V4. It’s easy to set it to zoom on alt-click, though. I’ve done so here:
Note that there’s a known MathJax bug that needs to be addressed with a little CSS, as described in this GitHub Issue. I’ve included that fix in this code as well.
Loading options
As it stands, AsciiMath cannot be turned on and Accessibility cannot be turned off. I think that’s down to the way that submodules are loaded sequentially inload-mathjax.js.
As I stated in my last message, it’s much more common to pre-define a window.MathJax object that specifies which components you want. The MathJax object is redefined when the main script is loaded. That’s how I was able to get this working in my V3 version. I think I could incorporate that approach in your code base during the first part of next week, if you’d like me to try?
Once we get options figured out, it might also be worth considering if there are new options available in V4 that should be included.
The rich editor
This is just great - I’m super happy to see it!
I wonder if it would be possible to get a sparkly AI context menu available within the modal? I ask because students (and professors 
) sometimes have difficulty typing LaTeX. A little AI proofreader can make that so much smoother. I’ve incorporated that into my classroom Discourse and am looking forward to using it this coming semester.
OK, I’m sure there’s a lot more, but I’m about done for the day.
Thanks so much!!! 
