Event loop peculiarities

sigh.js

(function(){
  var dudeEvent = new CustomEvent('dude');
  var body = document.querySelector('body');
  body.addEventListener('dude', function(){
    console.log('dude listener');
    console.log('alerting')
    alert('wat');
  });
  function a(){ 
    body.dispatchEvent(dudeEvent); 
    console.log('still in a'); 
  }
  a();
  function b(){
    setTimeout(body.dispatchEvent.bind(body, dudeEvent),0);
    console.log('still in b');
  }
  b();
})();

//output in chrome/firefox
//"dude listener"
//"alerting"
//"still in a"
//"still in b"
//"dude listener"
//"alerting"