Inside of this canvas is a frequency modulator with some sampling functionality. You can control the interface with keys or a mouse. For starting to play and turn off, you use the p key. The r key starts and stops the recording. There are two volume sliders. The a and s keys control the volume on the modulator. And you use the z and x keys to control the sample volume. With the c key, you clean the sampler or empty it. There will come a button for that later together whit some other things. Update: I have added the h key, and it will hold or freeze the tone.
There is some bug in the p5js library or WebKit 1 that distorts the sound from the sampling. So this is not usable, but just a big enough programming challenge that it has been worth doing just for the practice.