I made a basic 16 step sequencer using many of the ideas shown there, using pure JS. You can check out the source code in gitlab to see how they can be implemented.

It also allows you to go beyond the 12 note western scale, though it doesn’t do any ratio tunings.

https://newdawnowl.itch.io/microtonal-grid
https://gitlab.com/NewDawnOwl/microtonalgrid