Double Tap in Articulate Storyline

var lastTapTime = 0;
var tapCount = 0;
var player = GetPlayer();
player.SetVar("doubleTap",false);
document.addEventListener('touchend', function(event) {
  var currentTime = new Date().getTime();
  var tapTime = currentTime - lastTapTime;
  if (tapTime < 500 && tapTime > 0) {
    tapCount++;
    if (tapCount === 2) {

      // double tap detected
      // do something here

        player.SetVar("doubleTap",true);
         player.SetVar("doubleTap",false);
      tapCount = 0;
    }
  } else {
    tapCount = 1;
  }
  lastTapTime = currentTime;
}, false);