Workshop › Klondike Solitaire › Step 21 of 40

Move cards by the rules

What we are doing

tryMove(from, index, to) moves the card at index and every card on top of it from one pile to another, if the rules allow it: to a foundation only one card that canFound, to a column a card that canStack, never onto the stock or the waste.

```js
// Move cards from index onwards of pile `from` to pile `to`, if the rules allow it.
function tryMove(from, index, to) {
  const cards = piles[from].slice(index)
  if (from === to || !cards.length) return false
  const allowed = to[0] === 'f' ? cards.length === 1 && canFound(cards[0], piles[to]) : to[0] === 't' && canStack(cards[0], piles[to])
  if (!allowed) return false
  piles[to].push(...piles[from].splice(index))
  return true
}
```

What it means

slice(index) copies the cards from index to the end without changing the pile; we only look at them.
Moving onto the same pile, or moving nothing, is not allowed.
allowed: to a foundation, one card that canFound; otherwise it must be a column and canStack. The stock and the waste fail both.
splice(index) cuts those cards off the source; push(...cards) adds them one by one to the target (... spreads the array into separate items).

Your turn

Above the hit comment line (// Which card, ...), write tryMove with its comment and leave an empty line after it.

Skills: Arrays and objects, Game states

← Rule 2: building a foundation Turn over the uncovered card →

All steps