createCanvas(400, 400);

}

​

let voices = [{note: 0, playing: false}, {note: 0, playing: false}, {note: 0, playing: false}];

let releaseOrder = [0,1,2]; //voice numbers in release order, old > new

function draw() {

  background(220);

}

​

function keyPressed() {

  if (keyCode < 65 || keyCode > 90) return; //a-z

  let freeVoice = releaseOrder.find(voice => !voices[voice].playing);

  if (freeVoice > -1) {

    voices[freeVoice].playing = true;

    voices[freeVoice].note = keyCode;

  }

  print('pressed ' + JSON.stringify(voices));

}

​

function keyReleased() {

  if (keyCode < 65 || keyCode > 90) return; //a-z

  let matchedVoice = voices.findIndex(voice => voice.playing && voice.note == keyCode);

  if (matchedVoice > -1) {

    voices[matchedVoice].playing = false;

    //find voice in releaseOrder

    let roIndex = releaseOrder.findIndex(ro => ro == matchedVoice);

    releaseOrder.splice(roIndex, 1); //remove

    releaseOrder.push(matchedVoice); //re-add at end

    print('releaseOrder ' + JSON.stringify(releaseOrder) + '\n');

  }

  print('released ' + JSON.stringify(voices));

}