The data read-only property of the MIDIMessageEvent interface returns the MIDI data bytes of a single MIDI message.

A Uint8Array.

In the following example midimessage events are listened for on all input ports. When a message is received the value of data is printed to the console.

inputs.forEach((input) => {
  input.onmidimessage = (message) => {
    console.log(message.data);
  };
});