Workshop › Minesweeper › Step 17 of 26

A flag protects its cell

What we are doing

A flagged cell cannot be opened by a click, and the flood fill steps around it. One misclick near the end would otherwise ruin a long game.

```js
function reveal(start) {
  if (start.revealed || start.flagged) return

    if (cell.revealed || cell.flagged) continue
```

What it means

• reveal returns at once for a flagged cell.
• The flood skips flagged cells the same way it skips open ones.

Your turn

Add || start.flagged to the first line of reveal, and || cell.flagged to the continue line of the flood.

Skills: Game states

← Flags with the right button Draw the flags →

All steps

1. A grid of cell objects
2. The canvas and the pen
3. Draw the field
4. Draw every frame
5. Neighbours
6. Mines, but not under the first click
7. Shuffle the candidates
8. Count the mines around
9. Open a cell
10. Open cells look different
11. Coloured numbers
12. Click to open
13. Stepping on a mine
14. Show the mines
15. Flood fill
16. Flags with the right button
17. A flag protects its cell
18. Draw the flags
19. Mines left
20. Winning
21. The end and a new game
22. What time is it?
23. The clock
24. Stop the clock
25. The best time
26. Build it yourself: wrong flags