Workshop › Tetris-style Blocks › Step 14 of 32

Turn with Up

What we are doing

Turning is like moving: work out the turned shape, and use it only if it fits. The Up arrow or x turns the piece.

```js
function tryRotate() {
  const turned = rotate(piece.shape)
  if (!fits(turned, piece.x, piece.y)) return false
  piece.shape = turned
  return true
}

  if (event.key === 'ArrowUp' || event.key === 'x') tryRotate()
```

What it means

• turned is a new, rotated matrix; piece is not touched yet.
• Only if it fits at the same place does it become the piece's shape.
• || means "or": the Up arrow or x.

Your turn

1. Write tryRotate under tryMove.
2. In the key listener, under the ArrowRight line, write the ArrowUp line.

Skills: Keyboard and mouse input, Collision detection

← Turn a matrix Wall kicks →

All steps

1. The well
2. The board as rows of numbers
3. Draw one cell
4. Draw the whole board
5. The number is the color
6. A piece is a small grid
7. A list of shapes
8. All seven pieces
9. Does it fit inside the well?
10. Blocks are in the way
11. Try, then move
12. Move with the arrows
13. Turn a matrix
14. Turn with Up
15. Wall kicks
16. Falling by itself
17. A random piece at the top
18. Land and lock
19. One function starts a game
20. When the pile reaches the top
21. Game Over on screen
22. Play again
23. Clear full rows
24. Points for lines
25. The side panel
26. Levels
27. Faster every level
28. A fair bag of pieces
29. The next piece
30. Drop it
31. The ghost piece
32. Build it yourself: hold a piece