code: function(){
  
  			// Update the next frame
  			updateId = requestAnimationFrame(update);
  
  			var now = Date.now();
  			if (emitter)
  				emitter.update((now - elapsed) * 0.001);
  
  			framerate.innerHTML = (1000 / (now - elapsed)).toFixed(2);
  
  			elapsed = now;
  
  			if(emitter && particleCount)
  				particleCount.innerHTML = emitter.particleCount;
  
  			// render the stage
  			renderer.render(stage);
  		}
docs: Update function every frame