1.5.2 • Public • Published

    JZZ: MIDI library for Node.js and web-browsers

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    JZZ.js allows sending, receiving and playing MIDI messages in Node.js and all major browsers in Linux, MacOS and Windows. Some features are available on iOS and Android devices.

    JZZ.js enables Web MIDI API in Node.js and those browsers that don't support it, and provides additional functionality to make developer's life easier.

    For the best user experience, it's highly RECOMMENDED (though not required) to install the latest version of Jazz-Plugin and browser extensions from Chrome Web Store or Mozilla Add-ons or Apple App Store.


    • MIDI In/Out
    • User-defined MIDI nodes
    • MIDI files
    • MPE
    • SMPTE
    • Additional modules


    npm install jzz --save
    or yarn add jzz
    or get the full development version and minified scripts from Github

    Note: in the (unlikely) case you get into trouble installing the midi-test module, that requires special system configuration, you can safely remove it from the devDependencies by running npm remove midi-test --save-dev.


    Plain HTML
    <script src="JZZ.js"></script>
    CDN (jsdelivr)
    <script src="https://cdn.jsdelivr.net/npm/jzz"></script>       // the latest version, or
    <script src="https://cdn.jsdelivr.net/npm/jzz@1.5.2"></script> // any particular version
    CDN (unpkg)
    <script src="https://unpkg.com/jzz"></script>       // the latest version, or
    <script src="https://unpkg.com/jzz@1.5.2"></script> // any particular version
    CommonJS (Browserify and Node.js command line applications)
    var JZZ = require('jzz');
    require(['JZZ'], function(JZZ) {
    import * as JZZ from 'jzz';

    Web MIDI API

    (Node.js example)
    var navigator = require('jzz');
    navigator.requestMIDIAccess().then(onSuccess, onFail);
    // ...
    navigator.close(); // This will close MIDI inputs,
                       // otherwise Node.js will wait for MIDI input forever.
    // In browsers the funcion is neither defined nor required.


    MIDI Output/Input
    JZZ().or('Cannot start MIDI engine!')
         .openMidiOut().or('Cannot open MIDI Out port!')
         .wait(500).send([0x90,60,127]) // note on
         .wait(500).send([0x80,60,0]);  // note off
    JZZ().openMidiIn().or('Cannot open MIDI In port!')
         .and(function() { console.log('MIDI-In: ', this.name()); })
         .connect(function(msg) { console.log(msg.toString()); })
    Connecting MIDI nodes
    var input = JZZ().openMidiIn();
    var output = JZZ().openMidiOut();
    var delay = JZZ.Widget({ _receive: function(msg) { this.wait(500).emit(msg); }});
    Helpers and shortcuts
    // All calls below will do the same job:
    port.send([0x90, 61, 127]).wait(500).send([0x80, 61, 0]);   // arrays
    port.send(0x90, 61, 127).wait(500).send(0x80, 61, 0);       // comma-separated
    port.send(0x90, 'C#5', 127).wait(500).send(0x80, 'Db5', 0); // note names
    port.noteOn(0, 'C#5', 127).wait(500).noteOff(0, 'B##4');    // helper functions
    port.note(0, 'C#5', 127, 500);                              // another shortcut
    port.ch(0).noteOn('C#5').wait(500).noteOff('C#5');          // using channels
    port.ch(0).note('C#5', 127, 500);                           // using channels
    Asynchronous calls
    // in the environments that support async/await:
    async function playNote() {
      var midi = await JZZ();
      var port = await midi.openMidiOut();
      await port.noteOn(0, 'C5', 127);
      await port.wait(500);
      await port.noteOff(0, 'C5');
      await port.close();
    // or:
    async function playAnotherNote() {
      var port = await JZZ().openMidiOut();
      await port.noteOn(0, 'C5', 127).wait(500).noteOff(0, 'C5').close();
    Virtual MIDI ports
    var logger = JZZ.Widget({ _receive: function(msg) { console.log(msg.toString()); }});
    JZZ.addMidiOut('Console Logger', logger);
    // now it can be used as a port:
    var port = JZZ().openMidiOut('Console Logger');
    // ...
    // substitute the native MIDIAccess
    // to make virtual ports visible to the Web MIDI API code:
    navigator.requestMIDIAccess = JZZ.requestMIDIAccess;
    Frequency / MIDI conversion
    JZZ.MIDI.freq('A5'); // => 440
    JZZ.MIDI.freq(69);   // => 440
    JZZ.MIDI.freq(69.5); // => 452.8929841231365
    // from frequency:
    JZZ.MIDI.midi(440);  // => 69
    JZZ.MIDI.midi(450);  // => 69.38905773230853
    // or from name:
    JZZ.MIDI.midi('A5'); // => 69

    Additional modules

    Testing your MIDI application

    Check the Getting Started page and the API reference for more information...


    npm i jzz

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