The MIDIAccess interface of the Web MIDI API provides methods for listing MIDI input and output devices, and obtaining access to those devices.

MIDIAccess.inputs Read only

Returns an instance of MIDIInputMap which provides access to any available MIDI input ports.

MIDIAccess.outputs Read only

Returns an instance of MIDIOutputMap which provides access to any available MIDI output ports.

MIDIAccess.sysexEnabled Read only

A boolean attribute indicating whether system exclusive support is enabled on the current MIDIAccess instance.

MIDIAccess.statechange_event

Called whenever a new MIDI port is added or an existing port changes state.

The Navigator.requestMIDIAccess() method returns a promise that resolves with a MIDIAccess object. Information about the input and output ports is returned.

When a port changes state, information about that port is printed to the console.

navigator.requestMIDIAccess().then((access) => {
  // Get lists of available MIDI controllers
  const inputs = access.inputs.values();
  const outputs = access.outputs.values();

  access.onstatechange = (event) => {
    // Print information about the (dis)connected MIDI controller
    console.log(event.port.name, event.port.manufacturer, event.port.state);
  };
});