Workshop › Tic-tac-toe › Step 12 of 33

Make a move

What we are doing

A move puts the current player's mark in a cell, then hands the turn to the other player. We remember whose turn it is in player and write the move as a function play(index).

```js
let player = 'X'

function play(index) {
  board[index] = player
  player = player === 'X' ? 'O' : 'X'
}
```

What it means

• player holds whose turn it is.
• play(index) takes a cell number as a parameter.
• board[index] = player puts the mark in that cell of the array.
• The last line switches the turn: X becomes O, O becomes X.

Your turn

1. Under the board line, write let player = 'X'.
2. Leave an empty line and write the play function, above function draw() {.

Skills: Game states, Functions

← A color for each mark No playing on a taken cell →

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