There are lots of websynths that respond to MIDI note messages, and I've seen some that respond to CCs as well -- e.g. the midi-synth [1] by Chris Wilson (editor of the WebAudio and WebMIDI specs) -- but in that case, the CC messages are hardcoded to the UI. (It also doesn't support 14-bit messages.)
In 106.js, every UI control is arbitrarily assignable to any MIDI CC message, so you can map it to your device however you like. That's a feature I'm used to ("MIDI learn") from desktop DAWs, but haven't seen in any other websynths yet.
You won't be able to see the UI for this feature at all unless you've got a MIDI controller plugged in, though.
Hm, yeah, that would be a cool thing to publish separately. The MIDI mapping code is pretty much isolated to these two objects [1] [2], but I'd have to do a little thinking about how people would want to use it, and separating it from Backbone would take some work.
In 106.js, every UI control is arbitrarily assignable to any MIDI CC message, so you can map it to your device however you like. That's a feature I'm used to ("MIDI learn") from desktop DAWs, but haven't seen in any other websynths yet.
You won't be able to see the UI for this feature at all unless you've got a MIDI controller plugged in, though.
[1] https://github.com/cwilso/midi-synth