Workshop › Klondike Solitaire › Step 20 of 40

Rule 2: building a foundation

What we are doing

A foundation is built in one suit, from the ace up: an empty one takes only an ace, then the 2 of the same suit, and so on. canFound has the same shape as canStack.

```js
// Foundation: same suit, one higher, starting from the ace.
function canFound(card, pile) {
  const under = last(pile)
  if (!under) return card.rank === 1
  return under.suit === card.suit && under.rank === card.rank - 1
}
```

What it means

• An empty foundation (!under) takes only an ace, rank 1.
• Otherwise the card under it must have the same suit and be one rank lower.

Your turn

Under canStack, leave an empty line and write canFound with its comment.

Skills: Functions

← Rule 1: building a column Move cards by the rules →

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