The forthcoming Wax 2 web based word processor (1.0 release shortly) can allow us to take advantage of some nice ProseMirror plugins including this wonderful addition for math:
The interaction model is quite nice – typing $$ immediately drops you into block math mode and typing $ … $ assigns marks out inline math. Moving the cursor to a math block breaks out the syntax for editing. It works pretty nicely. The below image is from the projects repo (there are more images there, check it out!):
This is a very interesting model for math editing and something we can implement in Wax 2.