I’ve kind of flipped things around, now focused on learning the Web Audio API via BASIC Anywhere Machine first, with thoughts about putting what I learn into a TiddlyWiki music synthesizer/compozer later.
To see quality of sounds at various frequencies with played in all four waveforms (sine, square, sawtooth, and triangle), give this BASIC Anywhere Machine sample program a spin. (NOTE: requires a physical keyboard to select an octave, so will not currently work with touch devices.)
Aside, if you geek out on this kind of stuff, a very cool article: Let's Learn About Waveforms