The sysexEnabled read-only property of the MIDIAccess interface indicates whether system exclusive support is enabled on the current MIDIAccess instance.

A boolean value.

The Navigator.requestMIDIAccess() method returns a promise that resolves with a MIDIAccess object. Printing the value of sysexEnabled to the console returns a boolean value, which is true if system exclusive support is enabled.

navigator.requestMIDIAccess().then((access) => {
  console.log(access.sysexEnabled);
});