This is something I currently work on occasionally and so far only bits and pieces exist as a rudimentary prototype. Still, I thought I share this in case there are people who are interested programming patterns/OOP in Javascript and like to help to find ways to implement this well (aka with maintainable code).
The tool allows to quickly “sketch” user interfaces. If figma would be a tool for drawing blueprints, this is for quickly trying an idea with sharpie on a sticky note. Ideally, the UI is compact enough to embed the tool in an issue tracker, much like a WYSIWYG-text editor is embeddable.
There is no live-collaboration (since postits are usually to small for several people to draw at the same time!). Rather, there should be the possibility to copy another sketch and alter it. This keeps the collaboration model simple and the history transparent.
What works so far is the basic object model, and drag and drop with auto-grouping which is a neat alternative to stack management with send-forward, send-backward etc.