Workshop › Missile Command-style Defense › Step 16 of 35

Explode on arrival

What we are doing

An interceptor that arrives becomes an explosion. Every frame each explosion gets one frame older, and old ones are removed.

```js
let blasts // explosions: { x, y, age }

  blasts = []

      blasts.push({ x: s.x, y: s.y, age: 0 })

  for (const b of blasts) b.age += 1
  blasts = blasts.filter((b) => b.age < BLAST_FRAMES)
```

What it means

• An arriving interceptor adds a blast of age 0 at its position.
• for (const b of blasts) b.age += 1: a loop with a single command can be written on one line.
• filter keeps only the blasts younger than BLAST_FRAMES.

Your turn

1. Under let shots ... write let blasts with its comment; in reset, under shots = [], write blasts = [].
2. In update, under s.done = true, write the blasts.push line.
3. Under the shots = shots.filter(...) line, leave an empty line and write the two blast lines.

Skills: Game states

← An explosion that grows and shrinks Draw the explosions →

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