midi-interface for midi.city

midi.js

if (navigator.requestMIDIAccess) {
  var keys = 'AWSEDFTGYHUJKOLP;'

  function send(note, velocity) {
    if (note >= 48 && note <= 64) {
      var i = keys.charCodeAt(note-48);
      document.dispatchEvent(new KeyboardEvent('key' + (velocity == 0 ? 'up' : 'down'), {'keyCode': i, 'which': i}));
    }
  }

  navigator.requestMIDIAccess().then(
    function(access) {
      for (var input of access.inputs.values()) {
        input.onmidimessage = function(midi) {
          switch (midi.data[0] & 0xf0) {
            case 0x80:
              send(midi.data[1], 0)
              break;
            case 0x90:
              send(midi.data[1], midi.data[2])
              break;
          }
        }
      }
    },
    function(){
      alert('No access :(')
    }
  );
} else {
  alert('No MIDI-support :(')
}