Ep 2

gistfile1.js

var MidiStream = require('midi-stream');

var push = MidiStream('Ableton Push 2 User Port');

push.on('data', function(data) {
  var instruction = data[0];
  var note = data[1] - 36;
  var row = Math.floor(note / 8);
  var column = note % 8;

  if(instruction === 144) {
    playRowColumn(row, column, randomVelocity());
    playRowColumn(7 - row, 7 - column, randomVelocity());
  }
});

function playRowColumn(row, column, velocity, delay) {
  row = row % 8;
  column = column % 8;
  var note = (row * 8) + column;
  play(note, velocity, delay);
}

function play(note, velocity, delay) {
  setTimeout(() => push.write([144, note + 36, velocity]), delay || 0);
}

function randomVelocity() {
  return Math.floor((Math.random() * 128));
}