web-audio-scheduler-metronome-example.js

let audioContext = new AudioContext();
let sched = new WebAudioScheduler({
  context: audioContext
});

function metronome(e) {
  sched.insert(e.playbackTime + 0.000, ticktack, { frequency: 880, duration: 1.00 });
  sched.insert(e.playbackTime + 0.500, ticktack, { frequency: 440, duration: 0.05 });
  sched.insert(e.playbackTime + 1.000, ticktack, { frequency: 440, duration: 0.05 });
  sched.insert(e.playbackTime + 1.500, ticktack, { frequency: 440, duration: 0.05 });
  sched.insert(e.playbackTime + 2.000, metronome);
}

function ticktack(e) {
  let t0 = e.playbackTime;
  let t1 = t0 + e.args.duration;
  let osc = audioContext.createOscillator();
  let amp = audioContext.createGain();

  osc.frequency.value = e.args.frequency;
  osc.start(t0);
  osc.stop(t1);
  osc.connect(amp);

  amp.gain.setValueAtTime(0.5, t0);
  amp.gain.exponentialRampToValueAtTime(1e-6, t1);
  amp.connect(masterGain); // <-- connect to master gain, instead of AudioDestinationNode

  sched.nextTick(t1, () => {
    osc.disconnect();
    amp.disconnect();
  });
}

function start() {
  sched.start(metronome);
}

function stop() {
  sched.stop(true);
}


let masterGain = null;

sched.on("start", () => {
  masterGain = audioContext.createGain();
});

sched.on("stop", () => {
  masterGain.disconnect();
  masterGain = null;
});