Workshop › Connect Four › Step 1 of 38

Connect Four: A dark background

Drop discs into the columns and get four in a row before the computer does. A 2D array with gravity, a falling animation, checking lines in four directions, and a computer opponent that wins, blocks and thinks one move ahead.

What we are doing

We are building Connect Four: drop discs into columns and get four in a row before the computer does. Everything is painted on a <canvas>. First we find it, take its drawing tool and paint the background dark.

```js
const canvas = document.getElementById('game')
const ctx = canvas.getContext('2d')

ctx.fillStyle = '#0f172a'
ctx.fillRect(0, 0, canvas.width, canvas.height)
```

What it means

• document.getElementById('game') finds the canvas; const canvas = gives it a name.
• getContext('2d') gives its drawing tool, ctx.
• fillStyle picks a color; fillRect(x, y, width, height) paints a rectangle, here the whole canvas.

Your turn

Write the code under the three comment lines and press Run.

Skills: Drawing on a canvas

A drawing function →

All steps

1. A dark background
2. A drawing function
3. The blue board
4. One hole
5. A whole row
6. All 42 holes
7. The board in memory
8. Discs in their colors
9. Draw every frame
10. Where does the disc land?
11. Play a column
12. Taking turns
13. Click to play
14. The next disc
15. Whose turn?
16. Playing with the keyboard
17. Keys 1 to 7
18. A disc on its way
19. Gravity
20. Watch it fall
21. Inside the board?
22. Walking along a line
23. Four in a row?
24. We have a winner
25. Circle the four
26. Who won?
27. A draw
28. Play again
29. Try a move and take it back
30. Win, or block
31. Don't help the player
32. Prefer the middle
33. The computer's turn
34. Only on your turn
35. You and the computer
36. Counting wins
37. Show the score
38. Build it yourself: the loser starts