// Prepare the AudioContext instance
var context = new AudioContext();
var synth = new JSSynth.Synthesizer();
synth.init(context.sampleRate);

// Create AudioNode (ScriptProcessorNode) to output audio data
var node = synth.createAudioNode(context, 8192); // 8192 is the frame count of buffer
node.connect(context.destination);

// Load your SoundFont data (sfontBuffer: ArrayBuffer)
synth.loadSFont(sfontBuffer).then(function () {
    // Load your SMF file data (smfBuffer: ArrayBuffer)
    return synth.addSMFDataToPlayer(smfBuffer);
}).then(function () {
    // Play the loaded SMF data
    return synth.playPlayer();
}).then(function () {
    // Wait for finishing playing
    return synth.waitForPlayerStopped();
}).then(function () {
    // Wait for all voices stopped
    return synth.waitForVoicesStopped();
}).then(function () {
    // Releases the synthesizer
    synth.close();
}, function (err) {
    console.log('Failed:', err);
    // Releases the synthesizer
    synth.close();
});