Workshop › Missile Command-style Defense › Step 17 of 35

Draw the explosions

What we are doing

Each explosion is a filled circle of its current radius. It flickers between yellow and orange every three frames.

```js
for (const b of blasts) {
  ctx.fillStyle = b.age % 6 < 3 ? '#fde047' : '#fb923c'
  ctx.beginPath()
  ctx.arc(b.x, b.y, radius(b), 0, Math.PI * 2)
  ctx.fill()
}
```

What it means

• % is the remainder: b.age % 6 counts 0 to 5 again and again, so the color changes every 3 frames.
• arc(x, y, r, 0, Math.PI * 2) describes a full circle; fill() paints it.

Your turn

In draw, under the interceptor lines loop, write the explosion loop.

Skills: Drawing on a canvas

← Explode on arrival Impacts explode too →

All steps

1. Six cities to protect
2. Your missile base
3. Draw again and again
4. Cities that can fall
5. Rubble
6. Move towards a point
7. Launch an enemy missile
8. One missile a second
9. Missiles on their way
10. Smoke trails
11. Impact
12. Fire an interceptor
13. Click the sky
14. Interceptors fly
15. An explosion that grows and shrinks
16. Explode on arrival
17. Draw the explosions
18. Impacts explode too
19. Caught in the blast
20. Chain reactions
21. Only your explosions count
22. Points for every missile
23. Show the score
24. Limited ammo
25. Waves
26. Each wave is harder
27. The end of a wave
28. The end
29. Play again
30. Wave, ammo and messages
31. Launch from anywhere
32. Some missiles will split
33. Split into three
34. A high score
35. Build it yourself: a crosshair