<script>

var ac = new AudioContext();

var runningPromise = new Promise(resolve => {

  ac.onstatechange = event => {

    if (ac.state == "running") {

      resolve();

    }

  };

});

var osc = ac.createOscillator();

osc.connect(ac.destination);

osc.start(0);

osc.stop(osc.context.currentTime + 2.0);

var suspendPromise;

function suspendAC() {

  runningPromise.then(() => {

    suspendPromise = ac.suspend();

  });

}

var resumePromise;

function resumeAC() {

  suspendPromise.then(() => {

    resumePromise = ac.resume();

  });

}

function closeAC() {

  resumePromise.then(() => {

    ac.close();

  });

}

</script>