title: addEventListener with requestAnimationFrame
body: <p>I'm using <code>window.requestAnimationFrame</code> to create a game loop. </p>
  
  <p>Everything works great, but when I try to add an event listener it fires hundreds of times really fast.</p>
  
  <p>I've tried using a closure, but that doesn't seem to work.</p>
  
  <pre><code>game.update = function(){
     //code that runs every frame
     window.addEventListener('keydown', function(){
        console.log("message");
     },false);
  }
  </code></pre>
  
  <p>I want to call a function <strong>ONCE</strong> on the keydown event not multiple times.</p>