Workshop › Space Invaders-style › Step 7 of 21

A short reload

What we are doing

Holding Space should not fire a stream of bullets. After a shot, the next one can only come 350 milliseconds later. We keep the time of each frame in now and the time of the last shot in lastShot.

```js
const COOLDOWN = 350 // milliseconds between shots
let lastShot = -COOLDOWN
let now = 0

  if (now - lastShot < COOLDOWN) return
  lastShot = now

function loop(time) {
  now = time
```

What it means

• loop receives the time from the browser and keeps it in now.
• A shot is refused while less than 350 ms have passed since the last one.
• lastShot starts at -350, so the very first shot is allowed at once.

Your turn

1. Under BULLET_SPEED, write COOLDOWN; under bullets, write lastShot and now.
2. At the top of shoot, write the two cooldown lines.
3. Give loop the time parameter and keep it in now.

Skills: Game states, The game loop

← Bullets fly The invaders →

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