Workshop › Puzzle Bobble-style Bubble Shooter › Step 22 of 31

Only useful colors

What we are doing

Near the end, a color that is no longer on the board is useless. The shooter now only offers colors still there.

```js
// The colors still on the board, so the shooter never offers a useless one.
function pickColor() {
  const present = [...new Set(grid.flat().filter((color) => color >= 0))]
  const choices = present.length ? present : COLORS.map((_, i) => i)
  return choices[Math.floor(Math.random() * choices.length)]
}
```

What it means

• grid.flat() makes one list of every cell; filter keeps the bubbles; a Set keeps each color once.
• If the board is empty, any color will do.
• The random pick is an index into choices.

Your turn

Add the comment above pickColor and replace its body.

Skills: Arrays and objects

← Show the score Count the shots →

All steps

1. The night sky
2. One bubble
3. A grid of cells
4. Draw the grid
5. Bubbles that nest
6. The shooter
7. Aim upwards
8. Turn with the arrows
9. Aim with the pointer
10. Fire!
11. Fly
12. Bounce off the walls
13. Touching something?
14. Stick into the grid
15. Smaller steps
16. Six neighbours
17. Flood fill
18. Three in a row pop
19. Bubbles that fall
20. Cut them loose
21. Show the score
22. Only useful colors
23. Count the shots
24. The ceiling comes down
25. Win or lose
26. The danger line
27. The end message
28. Play again
29. Best score
30. A dotted guide
31. Build it yourself: swap bubbles