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midival is the library to handle MIDI messages in JavaScript (TypeScript) with ease. It provides simple programming interface to interact with both MIDI IN and MIDI OUT.

The library is currently in alpha state. Feel free to contribute, post bug reports, comments and ideas.

More information: midival.github.io


yarn add @midival/core

Getting started

To get started you need to initialise the library and ask for available devices:

import MIDIVal from "@midival/core";

.then(accessObject => {
    console.log("Inputs", accessObject.inputs);
    console.log("Outputs", accessObject.outputs);

Listening to devices

You can also listen to new devices and react when they are connected:

import MIDIVal from "@midival/core";

MIDIVal.onDeviceConnected(device => {
    console.log("Device", device);

You can also listen to disconnect events:

import MIDIVal from "@midival/core";

MIDIVal.onDeviceDisconnected(device => {
    console.log("Device", device);

Once you obtain reference to device, you can use it by creating MIDIValInput / MIDIValOutput object from it:

.then(accessObject => {
    const input = new MIDIValInput(accessObject.inputs[0]);

MIDI Inputs

Once you obtain access to the MIDI Input you can interact with it.

Note On

You can subscribe to note on.

input.onAllNoteOn((key, midiMessage) => {
    console.log("Note On:", key, "velocity:", cmidiMessage.data2);

You can also subscribe to a specific key:

input.onNoteOn(60, (midiMessage) => {
    console.log("C pressed with velocity", midiMessage.data2);

Note Off

You can subscribe to note off. The note off takes into account both Note Off message as well as Note On with Velocity 0.

input.onAllNoteOff((key, midiMessage) => {
    console.log("Note Off:", key);

You can also subscribe to a specific key:

input.onNoteOff(60, (midiMessage) => {
    console.log("C depressed with velocity", midiMessage.data2); // velocity should be 0.

Control Change

To listen to Control Change (MIDI CC) messages like modulation, synth parameter change and more, you can do the following:

input.onAllControlChange((param, midiMessage => {
    console.log(`Param: ${param}, value: ${midiMessage.data2}`);

You can also listen to the single control parameter (like Modulation wheel, Volume or Pan only). The full table with MIDI CC messages can be found in the official MIDI CC documentation.

input.onControlChange(7, (midiMessage) => {
    console.log('Volume change to value:', midiMessage.data2));

input.onControlChange(1, (midiMessage) => {
    console.log('Modulation Wheel value changed to:', midiMessage.data2);

Program Change

You can listen to program change messages:

input.onAllProgramChange((program, midiMessage) => {
    console.log(`Program ${program} changed to: ${midiMessage.data2}`);

You can also listen to a single program channel:

input.onProgramChange(1, (midiMessage) => {
    console.log(`Program 1 changed to:`, midiMessage.data2);

Poly Key Pressure

You can listen to Poly Key Pressure:

input.onAllPolyKeyPressure((key, midiMessage) => {});

you can listen to a specific key:

input.onPolyKeyPressure(5, (midiMessage) => { });


You can listen to systex message:

input.onSysex((midiMessage) => { });

All Sounds Off

You can listen to all sounds off message

input.onAllSoundsOff(() => { });

Reset All Controllers

You can listen to the signal to reset all controllers

input.onResetAllControllers(() => { });

Local Control Change

Under construction

All Notes Off

You can listen to all notes off

input.onAllNotesOff(() => { });

To Be Added

The following features are planned to be added to MIDI Input:

  • Omni Mode On
  • Omni Mode Off
  • Mode Mode On
  • Poly On
  • Better support for sysex


If you want to stop listening to all the messages and unregister all callbacks simply call:


MIDI Outputs

Under construction.

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