Workshop › Klondike Solitaire › Step 17 of 40

Hitting a card in a column

What we are doing

In a column the cards overlap, so a point can be inside several of them. The one drawn last is on top, so we test from the last card down, and the first match wins.

```js
if (key[0] === 't') {
  for (let i = pile.length - 1; i >= 0; i--) {
    const cy = cardY(key, i)
    if (y >= cy && y <= cy + CH) return { key, index: i }
  }
} else if (y >= TOP_Y && y <= TOP_Y + CH) return { key, index: pile.length - 1 }
```

What it means

• For a column, the loop runs i from the last card down to 0 and returns the first card whose rectangle contains y.
• else if handles the top row as before.

Your turn

In hit, replace the if (key[0] !== 't' && ...) line with the new lines.

Skills: Collision detection

← What is under the pointer? Tap the stock →

All steps

1. The green table
2. Draw one card
3. The face of a card
4. Red and black
5. A deck of 52
6. Shuffle
7. Piles in one object
8. Deal the seven columns
9. A place for every pile
10. Put the piles on the table
11. Fan out the columns
12. Outlines for empty places
13. Turn over a card
14. Space turns a card
15. Go through the stock again
16. What is under the pointer?
17. Hitting a card in a column
18. Tap the stock
19. Rule 1: building a column
20. Rule 2: building a foundation
21. Move cards by the rules
22. Turn over the uncovered card
23. Find where a card goes
24. Pick up a card
25. Tap to move
26. A move counter
27. Count the moves
28. Where did you grab it?
29. Follow the pointer
30. Draw the held cards at the pointer
31. Drop it where you want
32. Drop a king into an empty column
33. A clock
34. Winning
35. You won!
36. A new game
37. The best time
38. Snapshots of the table
39. Undo
40. Build it yourself: finish by itself