Audio Synthesis
recording
lamejs will encode audio.
Sequencing
- motor.js is a step sequencer library
- old school sequencing example from a MIDI player.
alternatively, one can use DSP as a sequencer, as with tone.js, which attempts to guarantee strong timing.
Webaudio information
There are too many resources online to list. Start here
accessing microphone getusermedia examples
Alternatives to WebAudio
phonegap/appcelerator + libpd?