Workshop › 2048 › Step 26 of 26

Build it yourself: undo

What we are doing

Everyone makes a bad move sometimes. Add an undo: the U key takes the last move back, board and score, once.

Your turn

Keep a copy of the board and the score before each real move. The U key (small or capital) restores them once; a second U does nothing until the next move. Undo also brings a finished game back to playing.

Skills: Game states, Arrays and objects

All steps

  1. The board
  2. Sixteen cells
  3. A grid of numbers
  4. A color for every number
  5. Numbers on the tiles
  6. Big numbers, smaller text
  7. Find the empty cells
  8. A new tile
  9. Two tiles to start
  10. Slide a row
  11. Merge equal tiles
  12. Move left
  13. The arrow key
  14. Only real moves count
  15. Right is left, reversed
  16. Up and down are columns
  17. Score
  18. Is there a move left?
  19. Game over
  20. Making 2048
  21. Win and lose screens
  22. Space to go on
  23. Best score
  24. Swipes
  25. A tap is not a swipe
  26. Build it yourself: undo