Workshop › Simon Says Colors › Step 18 of 27

Which pad is at a point?

What we are doing

To play with the mouse we must know which pad is under a point. padAt(x, y) answers -1 in the text strip, and otherwise 0 to 3 from the half of the board the point is in.

```js
function padAt(x, y) {
  if (y < TOP) return -1
  return (y - TOP < HALF ? 0 : 2) + (x < HALF ? 0 : 1)
}
```

What it means

• In the text strip (y < TOP) there is no pad: -1.
• Top half gives 0, bottom half 2; left half adds 0, right half 1. Bottom right: 2 + 1 = 3.

Your turn

Under press, leave an empty line and write padAt (above the keydown listener).

Skills: Functions

← Play with the keyboard Play with the mouse →

All steps

1. Get the canvas and the pen
2. A dark board
3. The first pad
4. Two colors for every pad
5. All four pads
6. A function that draws
7. Light a pad
8. Draw again and again
9. The sequence to remember
10. Show the round
11. Light a pad for a while
12. Go dark again
13. The computer shows a pad
14. Show the whole sequence
15. Watch, then your turn
16. Check each press
17. Play with the keyboard
18. Which pad is at a point?
19. Play with the mouse
20. Progress and mistakes
21. A function for a new game
22. Click to retry
23. Light up when pressed
24. Faster and faster
25. Save the best score
26. Show the best score
27. Build it yourself: no dawdling