Workshop › Tic-tac-toe › Step 6 of 33

The board as a list

What we are doing

The picture is only the look. The game also has to remember what is in each of the 9 cells. We keep that in an array of 9 strings: '' for empty, later 'X' or 'O'.

```js
let board = ['', '', '', '', '', '', '', '', '']
```

What it means

• [ ... ] is an array: a list in order, items separated by commas.
• '' is an empty string: an empty cell. A filled cell will hold 'X' or 'O'.
• Items are numbered from 0: board[0] is the top-left cell, board[8] the bottom-right one.
• let, because the board will change during the game.

Your turn

Under const CELL = 100, leave an empty line and write the board line. Press Run.

Skills: Arrays and objects, Game states

← Finish the grid A function that draws →

All steps

1. Get the canvas and the pen
2. Paint the board
3. The first grid line
4. Repeat with a loop
5. Finish the grid
6. The board as a list
7. A function that draws
8. Write an X
9. From cell number to position
10. Draw what the board holds
11. A color for each mark
12. Make a move
13. No playing on a taken cell
14. Listen for clicks
15. Which cell was clicked?
16. Clicks on any screen size
17. The eight winning lines
18. Find three in a row
19. Win, draw or go on
20. The round ends
21. Show who won
22. Light up the winning line
23. A function for a fresh round
24. Click to play again
25. A computer that picks a cell
26. The computer answers
27. Rule one: take the center
28. Rule two: win when you can
29. Rule three: block the opponent
30. Score a finished game
31. Look ahead: minimax
32. A computer that never loses
33. Build it yourself: keep score