StackOverflow New Question Sound Notification

so_notifier.js

(function () {
  'use strict';
 
  var model = {
    alarmActive: true
  };

  var controller = {
    init: function() {
      if (this.alreadyRunning()) {
        console.warn('Already notifying!');
        return;
      }
      view.init();
      view.update();
    },
    isAlarmActive: function() {
      return model.alarmActive;
    },
    notify: function() {
      if (model.alarmActive) {
        model.alarmActive = false;
        view.notify();
        view.update();
      }
    },
    reEnable: function() {
      model.alarmActive = true;
      view.update();
    },
    alreadyRunning: function() {
      if(window.w0lfNotifierRunning) {
        return true;
      }
      window.w0lfNotifierRunning = true;
    }
  };

  var view = {
    init: function() {
      this.domElement = document.getElementById('questions') || document.getElementById('qlist-wrapper');
      this.sound = new Audio("http://www.soundjay.com/button/sounds/button-14.mp3");
      
      this.chkSoundEnabled = document.createElement('input');
      this.chkSoundEnabled.type = 'checkbox';
      this.chkSoundEnabled.checked = true;
      var title = document.querySelector('h1');
      title.insertBefore(this.chkSoundEnabled, title.children[0]);
  
      this.domElement.addEventListener('DOMSubtreeModified', function(){
        view.handleDOMChange();
      });
    },
    handleDOMChange: function() {
      var newPostsPresent = this.domElement.querySelector('.new-post-activity');

      if (newPostsPresent) {
        controller.notify();
      } else {
        controller.reEnable();
      }
    },
    notify: function() {
      if(this.chkSoundEnabled.checked) {
        this.sound.play();
      }
    },
    update: function() {
      var active = controller.isAlarmActive();
      this.domElement.style.border = active ? '3px dotted green' : '3px dotted red';
    }
  };

  controller.init();
}());

Adapted to also work with codegolf.stackexchange.com