The open() method of the MIDIPort interface makes the MIDI device connected to this MIDIPort explicitly available.

If the port is successfully opened a new MIDIConnectionEvent is queued to the MIDIPort statechange and MIDIAccess statechange events, and the MIDIPort.connection property is changed to "open".

If the port is already open when this method is called, then the promise will resolve successfully.

None.

A Promise which resolves once access to the port has been successfully obtained.

InvalidAccessError DOMException

The promise is rejected with this error if the port is unavailable and cannot be opened.

The following example shows an output port being opened.

const output = midiAccess.outputs.get(portID);
output.open(); // opens the port