Update description of BasicPlatformer

index.js

 function update() {

          // Using the physics.arcade system, check if 'player' is colliding
          //  with any tiles within 'layer'. If so, seperate them.
          game.physics.arcade.collide(player, layer);

          // Reset the x (horizontal) velocity
          player.body.velocity.x = 0;

          // Check if the left arrow key is being pressed
          if (cursors.left.isDown)
          {
            // Set the 'player' sprite's x velocity to a negative number:
            //  have it move left on the screen.
            player.body.velocity.x = -hozMove;

            // Check if 'facing' is not "left"
            if (facing !== "left")
            {
              // Set 'facing' to "left"
              facing = "left";
            }
          }
          // Check if the right arrow key is being pressed
          else if (cursors.right.isDown)
          {
            // Set the 'player' sprite's x velocity to a positive number:
            //  have it move right on the screen.
            player.body.velocity.x = hozMove;
            
            // Check if 'facing' is not "right"
            if (facing !== "right")
            {
              // Set 'facing' to "right"
              facing = "right";
            }
          }
          
          // Check if the jumpButton (SPACEBAR) is down AND
          //  if the 'player' physics body is onFloor (touching a tile) AND
          //  if the current game.time is greater than the value of 'jumpTimer'
          //  (Here, we need to make sure the player cannot jump while alreay in the air
          //   AND that jumping takes place while the sprite is colliding with
          //   a tile in order to jump off it.)
          if (jumpButton.isDown && player.body.onFloor() && game.time.now > jumpTimer)
          {
            // Set the 'player' sprite's y velocity to a negative number
            //  (vertMove is -90) and thus have it move up on the screen.
            player.body.velocity.y = vertMove;
            // Add 650 and the current time together and set that value to 'jumpTimer'
            // (The 'jumpTimer' is how long in milliseconds between jumps.
            //   Here, that is 650 ms.)
            jumpTimer = game.time.now + 650;
          }

          // Check if 'facing' is "left"
          if (facing === "left") {
            // Set the 'player' to the second (1) frame
            //  ('facing' is "left")
            player.frame = 1;
          } else {
            // Set the 'player' to the first (0) frame
            //  ('facing' is "right").
            player.frame = 0;
          }

        }