midi-fx-octaver.js

function transpose(originalNote, steps) {
  var note = new originalNote.constructor();
  note.pitch = originalNote.pitch + steps;
  note.velocity = originalNote.velocity;
  return note;
}

function octaveUp() {
  return true;
}

function octaveDown() {
  return true;
}  

function HandleMIDI(event) {
	event.send();
	event.trace();
	
	if (event instanceof Note) {
    	if (octaveUp()) {
	    var oup = transpose(event, 12);
	    oup.send();
	    oup.trace();
	  }
	
	  if (octaveDown()) {
	    var odown = transpose(event, -12);
	    odown.send();
	    odown.trace();
	  }
	}
}