Workshop › Tetris-style Blocks › Step 2 of 32

The board as rows of numbers

What we are doing

The well's contents are a list of 20 rows, each a list of 10 numbers: 0 is an empty cell, any other number a filled one. emptyRow() makes one row of zeros.

```js
function emptyRow() {
  return Array(COLS).fill(0)
}

let board = Array.from({ length: ROWS }, emptyRow)
```

What it means

• Array(COLS).fill(0) makes an array of 10 slots and fills them with 0; return hands it back.
• Array.from({ length: ROWS }, emptyRow) makes 20 elements by calling emptyRow for each, so every row is its own array. board[19][0] is the bottom-left cell.

Your turn

Under const CELL = 24 leave an empty line and write emptyRow and board.

Skills: Arrays and objects

← The well Draw one cell →

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