Introducing JSMidi
JSMidi is a music production tool that works directly with your Digital Audio Workstation (DAW) via MIDI. Together with the JSMidi Atom Plugin you can live code and build songs in JavaScript right inside the Atom Text Editor. JSMidi uses the Web MIDI API built into the browser to control up to 16 MIDI tracks in real time.
To get started read the documentation on the JSMidi Github Page.