CTFd/CTFd/themes/core/static/js/events.js

var wc = new WindowController();

var sound = new Howl({
  src: [
    script_root + "/themes/core/static/sounds/notification.webm",
    script_root + "/themes/core/static/sounds/notification.mp3"
  ]
});

function connect() {
  window.ctfEventSource = new EventSource(script_root + "/events");

  window.ctfEventSource.addEventListener(
    "notification",
    function(event) {
      var data = JSON.parse(event.data);
      wc.broadcast("notification", data);
      render(data);
    },
    false
  );
}

function disconnect() {
  if (window.ctfEventSource) {
    window.ctfEventSource.close();
  }
}

function render(data) {
  ezal({
    title: data.title,
    body: data.content,
    button: "Got it!"
  });
  sound.play();
}

wc.notification = function(data) {
  render(data);
};

wc.masterDidChange = function() {
  if (this.isMaster) {
    connect();
  } else {
    disconnect();
  }
};