Workshop › Space Invaders-style › Step 19 of 21

Waves

What we are doing

When every invader is down, the wave number goes up and a new formation arrives. The wave is shown in the middle of the top bar.

```js
if (alive().length === 0) {
  wave += 1
  spawnWave()
  return
}

ctx.textAlign = 'center'
ctx.fillText('WAVE ' + wave, canvas.width / 2, 24)
```

What it means

• return ends this frame right after the new wave appears.
• textAlign = 'center' centers the text on the given x.

Your turn

1. In update, under the second stop line, start a new wave when none are left.
2. In draw, write the wave between the score and the lives.

Skills: Game states

← Play again Faster and faster →

All steps

1. The ship
2. The game loop
3. Move the ship
4. Stay on screen
5. Fire
6. Bullets fly
7. A short reload
8. The invaders
9. The march
10. Hit!
11. Score
12. They shoot back
13. Bombs fall
14. Lives
15. Game over
16. Best score
17. A wave in a function
18. Play again
19. Waves
20. Faster and faster
21. Build it yourself: an extra life