a library for writing MIDI files, reading MIDI files, and representing MIDI files as an intermediary JSON structure. nothing more, nothing less.

simply add a script tag to your page linking to the midi.js built script. this will expose a global MIDI object.

midi.js accepts a binary string as it's input. the example below shows how to parse a midi file selected from a file type input.

onFileChange = (fileInput) ->
  files = fileInput.files
  reader = new FileReader()

  reader.onload = (load_e) ->
    midi = new MIDI(load_e.target.result)
    console.log midi

  reader.readAsBinaryString(files[0])

instead of accepting a binary string, the MIDI constructor can also accept predefined header and track objects. additionally, any MIDI file can call write to return the encoded contents of the midi.

header =
  formatType: 0
  trackCount: 1
  ticksPerBeat: 96

track1 = [
  new MIDI.Events.TrackName(''),
  new MIDI.Events.TimeSignature(4, 4, 36, 8),
  new MIDI.Events.NoteOn(65, 100),
  new MIDI.Events.NoteOff(65, 64, 24),
  new MIDI.Events.NoteOn(70, 100, 168),
  new MIDI.Events.NoteOff(70, 64, 24),
  new MIDI.Events.EndOfTrack()]

midi = new MIDI(header, [track1])
console.log(midi.write())

two primary Gruntfile tasks are exposed for purposes of developement.

build - will compile coffeescript files, and build the requirejs distributed packages default - will run build, and setup a watcher to rebuild on file changes