WebMidi.enable(onSuccess, onFailure);

function onSuccess() {
    console.log("WebMidi enabled.");
}

function onFailure(err) {
    console.log("WebMidi could not be enabled.", err);
}

WebMidi.playNote(2, 76, 0.5);

WebMidi.addEventListener('pitchbend', function(e) {
    console.log("Pitch value: " + e.value);
});

// Enable WebMidi. 3 parameters: onSuccess handler, onFailure handler and boolean
// indicating if you want to use system exclusive messages (defaults to false).
WebMidi.enable(

  function() { 

    // Viewing available inputs and outputs
    console.log(WebMidi.inputs);
    console.log(WebMidi.outputs);

    // Getting the current time
    console.log(WebMidi.time);

    // Playing a note (note number 60 on the 1st channel [0] at half velocity)
    WebMidi.playNote(0, 60, 0.5);
    WebMidi.playNote(0, 60, 0.5, 1000);           // send a noteoff after 1 sec.
    WebMidi.playNote(0, 60, 0.5, 1000, 1000);     // wait 1 sec. before playing

    // Stopping a playing note
    WebMidi.stopNote(0, 60, 1);
    WebMidi.stopNote(0, 60, 0.5, 2000);           // wait 2 sec. before stopping

    // Send polyphonic aftertouch message
    WebMidi.sendKeyAftertouch(0, 60, 0.5);
    WebMidi.sendKeyAftertouch(0, 60, 0.5, 1000);  // wait 1 sec. before sending

    // Send control change value 127 to controller 1 (modulation) on channel 0
    WebMidi.sendControlChange(0, 1, 127);
    WebMidi.sendControlChange(0, 1, 127, 1000);     // wait 1 sec. before sending

    // Send channel aftertouch
    WebMidi.sendChannelAftertouch(0, 0.5);

    // Send pitch bend (between -1 and 1)
    WebMidi.sendPitchBend(0, -1);

    // Chaining method calls
    WebMidi.sendPitchBend(0, -1)
      .sendPitchBend(0, -0.5, 200)
      .sendPitchBend(0, 0, 400)
      .sendPitchBend(0, 0.5, 800)
      .sendPitchBend(0, 1, 1000);

    // Listening for a 'note on' message (on all channels)
    WebMidi.addEventListener(
      'noteon',
      function(e){ console.log(e); },
      'all'
    );

    // Listening for a 'note on' message (on channel 0 only)
    WebMidi.addEventListener(
      'noteon',
      function(e){ console.log(e); },
      0
    );

    // Listening to other messages works the same way (defaults to 'all' channels)
    WebMidi.addEventListener(
      'noteoff',
      function(e){ console.log(e); }
    );

    WebMidi.addEventListener(
      'pitchbend',
      function(e){ console.log(e); }
    );


    // The special 'statechange' event tells you that a device has been plugged or
    // unplugged. For system-wide events, you do not need to specify a channel.
    WebMidi.addEventListener(
      'statechange',
      function(e){ console.log(e); }
    );


    // You can also check and remove event listeners (in this case, you shouldn't use
    // anonymous methods).
    WebMidi.addEventListener('statechange', test);
    console.log("Has event listener: ",  WebMidi.hasEventListener('statechange', test) );
    WebMidi.removeEventListener('statechange', test);
    console.log("Has event listener: ",  WebMidi.hasEventListener('statechange', test) );

    function test(e) {
      console.log(e);
    }

  },

  function(m) {
    console.log("Could not enable MIDI interface: " + m);
  },

  true      // Whether to enable sysex or not. When set to 'true', it might trigger an
            // authorization prompt to the user. If you do not need it, leave it to false.

);