Workshop › Endless Runner › Step 17 of 19

Which keys are down?

What we are doing

To duck, we need to know whether the down arrow is held right now, not just when it was pressed. A keys object remembers every key that is down.

```js
const keys = {}

  keys[event.key] = true

  keys[event.key] = false
```

What it means

• keys starts empty. keys[event.key] = true stores a field named after the key, like keys.ArrowDown.
• A key that was never pressed is undefined, which counts as false.

Your turn

1. Under best, write const keys = {}.
2. Make the key lines the first lines of the keydown and keyup listeners.

Skills: Keyboard and mouse input

← Birds Duck →

All steps

1. The ground
2. The runner
3. Draw again and again
4. Gravity
5. Jump
6. Short hops
7. Tap to jump
8. Things that come at you
9. Cacti keep coming
10. Wait for the start
11. Crash
12. Try again
13. Faster and faster
14. Remember the best run
15. The score counter
16. Birds
17. Which keys are down?
18. Duck
19. Build it yourself: jump buffering