A significant weakness of Lively is missing proper debugger. Amber (https://amber-lang.net/) has one (but it is not plain JavaScript). The next complaint is that you need to host it.

Ideally, the system should have a good debugger and have an option to be self-hosted like TiddlyWiki (with an option to be served by a normal server). I did some experiment in this regard (https://pavel-krivanek.github.io/amber/amber.html - only "legacy IDE" work) but then you can save it and it will save the new version with all the changes you did as a self-hosted HTML file.