function checkGameEnd(winner) { //проверяем, не закончена ли игра
    if ((window.cells[0] == true) && (window.cells[1] == true) && (window.cells[2] == true)) ||
       ((window.cells[0] == true) && (window.cells[3] == true) && (window.cells[6] == true)) ||
       ((window.cells[0] == true) && (window.cells[4] == true) && (window.cells[8] == true)) ||
       ((window.cells[1] == true) && (window.cells[4] == true) && (window.cells[7] == true)) ||
       ((window.cells[2] == true) && (window.cells[5] == true) && (window.cells[8] == true)) ||
       ((window.cells[2] == true) && (window.cells[4] == true) && (window.cells[6] == true)) ||
       ((window.cells[3] == true) && (window.cells[4] == true) && (window.cells[5] == true)) ||
       ((window.cells[6] == true) && (window.cells[7] == true) && (window.cells[8] == true)) {
            document.getElementById('result').innerHTML = winner;
            document.getElementById('result').appendChild(document.createTextNode(' won!'));
    }
}