Apple Logic MIDI script to toggle notes

note-toggle.js

var notesOn = [];

function isNotePlaying(event) {
	for (var i = 0; i < notesOn.length; i++) {
		if (notesOn[i] && notesOn[i].pitch == event.pitch) {
			return i;
		}
	}
	
	return false;
}

function sendNoteOff(event) {
  var noteOffEvent = new NoteOff();
	noteOffEvent.pitch = event.pitch;
	noteOffEvent.channel = event.channel;
	noteOffEvent.velocity = 0;
	noteOffEvent.send();
}

function HandleMIDI(event)
{
	//event.trace();
	
	if (event instanceof NoteOn) {
	   var noteIndex = isNotePlaying(event)
		if (typeof noteIndex == 'number') {
			delete notesOn[noteIndex];
			sendNoteOff(event);
		} else {
			notesOn.push(event);
			event.send();
		}
		
		return;
	}
	
	if (event instanceof NoteOff) {
		return;
	}
	
	event.send();
}