Tic Tac Toe

[kuba1234567a]

I play tic-tac-toe and I have a problem because I can't do it.

I wanted to do that if button2 is X then it changes to button1 etc. over and over again, how can I do it.

          if(document.getElementById('button5').value=="X")
                {
                    document.getElementById('button2').value="O";
                    }