We will set the visual and initial placement of the player by using CSS styles. Append the following styles to the game.css file:

#player {
  position: absolute;
  width: 100px;
  height: 100px;
  background-image: url(../images/running.png);
  bottom: 100px;
}

Now, we use the translate function to set the lane position of the player:

#player.lane1 {-webkit-transform: translate3d(100px, 0, 0); }
#player.lane2 {-webkit-transform: translate3d(200px, 0, 0); }

Let's move to the logic part. In the player.js file, we append the following function that handles lane changing. To change the lane, we toggle the player element between the lane1 and lane2 classes:

player.changeLane = function(lane) {
  player.currentLane = lane;

  player.element.classList.remove('lane1...