The purpose is to make use of a dimension of the visual space previously unused to make diagrams more expressive.
Even if it's something simple like a node turning from green to red to convey it's shutting down. Maybe something like that before animations would be a text saying, "this node will shut down now", which takes reading/zooming into text.
I also think it can, if used well, result in diagrams that ⋆⋆spark joy⋆⋆. People like to see diagrams like that, even if it's not more utilitarian. I think sketch mode is an example of this. It changes the font to an objectively less readable one, yet I often hear people make all their D2 diagrams in sketch mode.
Coauthor of D2 here. Lately I've been noodling on the idea of expanding the animation capabilities. I think out loud a bit here, and if you have thoughts, would love to hear them:
Yeah that one's a community plugin vs an officially maintained one, which can have a range of activity from graveyard to some being maintained better than many of our official ones. That maintainer seems active on GitHub though and the d2-emacs plugin is his top pinned repo (https://github.com/andorsk), I think he'd be receptive if you let him know your interest!
1. It depends on what you value =). For some, those 2 you mentioned are enough. For others, it can be something like the our CLI doesn't require a chromium browser to render SVGs (https://news.ycombinator.com/item?id=31275754). It doesn't cover every difference, but we made a little comparison site if it helps: https://text-to-diagram.com
2. I'm not trying to advertise our paid product in this post about the open source product, but since you mentioned it, we make an IDE that adds the ability to lock in positions and dimensions: https://docs.terrastruct.com/tour/freehand
Unfortunately not, I've tried reaching out to GH folks but no dice. However it should be noted that d2.js, which enables client-side renders, didn't really become usable until this month and still isn't really officially released (kind of hidden). So, we'll see if the official release (soon™) changes things. If any D2-enjoyers reading this knows anyone on the GH frontend team, plz bend their ear =)
Check out the network tab in the d2 playground. It's powered by d2.js, a wrapper around a wasm port of d2, which we've recently been working on. Not super officially ready yet but soon to be, and will be a separate announcement.
Hello fellow devs. Just wanted to share a new feature we added this morning, though it's very alpha stage (already someone's filed a github issue for it hah)
I don't add this for D2 CLI because the outputs there are SVG, and this feature requires Javascript.