Facebook Messenger Notifications

var msgCount = document.getElementsByClassName('msg').length;
var personName = document.getElementsByTagName("title")[0].innerHTML;

$('#composerInput').onkeypress = function(event){
  if(event.which == 13){
    event.preventDefault();
    $('button._5y14._52cp').click();
  }
}

function notify() {
  var msgs = document.getElementsByClassName('msg');
  var lastMsg = msgs[msgs.length-1];

  var senderName = lastMsg.getElementsByClassName("actor")[0].innerHTML;
  if (senderName !== personName.replace(/\ \(\d+\)/, '')) {
    return;
  }

  var y = lastMsg.getElementsByTagName('div');
  var z = (y[y.length-1]).getElementsByTagName('span');
  var message = (z[z.length - 1]).innerHTML;
  var personPic = lastMsg.parentNode.parentNode.getElementsByTagName("img")[0].getAttribute("src");
  return new Notification(senderName, {body: message, icon: personPic});
} 

$('#messageGroup').addEventListener('DOMSubtreeModified',function(){
  if (msgCount != document.getElementsByClassName('msg').length){
    msgCount = document.getElementsByClassName('msg').length;
    notify();
  }
});