Workshop › Tower Defense › Step 2 of 42

A map of tiles

What we are doing

Two loops, one inside the other, visit every tile: for each row, every column. Each tile is painted green, so the whole map becomes grass.

```js
for (let row = 0; row < ROWS; row++) {
  for (let col = 0; col < COLS; col++) {
    ctx.fillStyle = '#3f6212'
    ctx.fillRect(col * TILE, TOP + row * TILE, TILE, TILE)
  }
}
```

What it means

• The outer loop counts row from 0 to 8, the inner one col from 0 to 11 for each row.
• The tile in row row, column col starts at col * TILE across and TOP + row * TILE down.

Your turn

At the end of the code, after an empty line, write the two loops.

Skills: Drawing on a canvas, Loops

← Measure the map Draw it every frame →

All steps

1. Measure the map
2. A map of tiles
3. Draw it every frame
4. The road as corners
5. Fill in the road
6. Draw the road
7. Walking by distance
8. Enemies on the road
9. Walk
10. Off the end of the road
11. Here they come
12. Towers
13. From a click to a tile
14. Click to build
15. Where can you build?
16. Show the gold
17. Show before you click
18. Show the range
19. Pick a target
20. Fire!
21. A hit hurts
22. Homing bullets
23. Fizzle out
24. Gold for every kill
25. Lives
26. Health bars
27. Build, then defend
28. Space starts a wave
29. The wave is over
30. Stronger every wave
31. Closer together
32. Out of lives
33. No building after the end
34. The most waves survived
35. The game over screen
36. Play again
37. The bottom bar
38. Click to start
39. A second tower: the cannon
40. Tower buttons
41. Splash damage
42. Build it yourself: sell a tower