Hey Jack, I built an I Ching tool earlier this year using arrow.js. I tried to stick with vanilla JS at first but it proved difficult to maintain. My tool uses a casting method that results in the same probabilities as when one uses the Yarrow Stalk method, but doesn't include a yarrow stalk simulation. I briefly considered creating a 3D simulation of the yarrow stalk casting method but never got around to it. I find it interesting that someone had a similar idea.

My I Ching tool is located at classicofchanges.com

Always happy to meet a fellow developer in this niche!

I checked out your site—having the full index on a single page is actually super handy for quick referencing.

And I totally relate to the 'Vanilla JS vs Framework' struggle. I ended up choosing Next.js precisely because managing the state for the complex probabilities (6/7/8/9) was giving me a headache. Respect for sticking to the raw math!