Workshop › Rhythm Lanes › Step 34 of 35

Lanes you can tap

What we are doing

On a phone the lanes themselves become the buttons: a tap anywhere in a lane presses it, through the same press. After the song, a tap plays again.

```js
// On a touch screen, each lane is its own big button.
canvas.addEventListener('pointerdown', (event) => {
  if (state === 'done') return reset()
  const rect = canvas.getBoundingClientRect()
  const x = ((event.clientX - rect.left) * canvas.width) / rect.width
  const lane = Math.floor((x - LEFT) / LANE_W)
  if (lane >= 0 && lane < LANES) press(lane)
})

    ctx.fillText('Space or tap to play again', canvas.width / 2, 318)
```

What it means

• pointerdown fires for a mouse button or a finger going down on the canvas.
• getBoundingClientRect() gives the canvas's box on the screen; the formula turns the page position into canvas pixels, even when the canvas is shown smaller on a phone.
• Math.floor((x - LEFT) / LANE_W) is the lane under the tap; outside 0 to 3 nothing happens.

Your turn

1. Above function draw() { write the comment and the pointerdown listener, with an empty line after it.
2. In the panel, change the last text to 'Space or tap to play again'.

Skills: Keyboard and mouse input

← Best score Build it yourself: a speed setting →

All steps

1. A stage for the notes
2. The first lane
3. Four lanes with a loop
4. The hit line
5. A function that draws
6. The song as text
7. From text to notes
8. The clock decides where
9. Draw the notes
10. A clock that ticks
11. The game loop
12. Lanes that light up
13. Keys for the lanes
14. Show the keys
15. Hit the closest note
16. Close enough in time
17. One press, one hit
18. A message on the screen
19. Say Hit
20. Let the message go
21. Perfect or good
22. Keep count
23. Missed notes
24. Score
25. Hits in a row
26. The multiplier
27. The song ends
28. Stop the clock
29. Accuracy
30. The grade
31. The results
32. Play again
33. Best score
34. Lanes you can tap
35. Build it yourself: a speed setting