The send() method of the MIDIOutput interface queues messages for the corresponding MIDI port. The message can be sent immediately, or with an optional timestamp to delay sending.

data

A sequence of one or more valid MIDI messages. Each entry represents a single byte of data.

timestamp Optional

A DOMHighResTimestamp with the time in milliseconds, which is the delay before sending the message.

None (undefined).

TypeError

Thrown if data is not a valid sequence, or does not contain a valid MIDI message.

InvalidAccessError DOMException

Thrown if data is a system exclusive message, and the MIDIAccess did not enable exclusive access.

InvalidStateError DOMException

Thrown if the port is disconnected.

In the following example a middle C note is sent immediately, followed by a note off message one second later.

function sendMiddleC(midiAccess, portID) {
  const noteOnMessage = [0x90, 60, 0x7f]; // note on middle C, full velocity
  const output = midiAccess.outputs.get(portID);
  output.send(noteOnMessage); //omitting the timestamp means send immediately.
  output.send([0x80, 60, 0x40], window.performance.now() + 1000.0); // timestamp = now + 1000ms.
}