Vanilla TicTacToe

var board = [
    ['', '', ''],
    ['', '', ''],
    ['', '', '']
]
var emptyBoard = [
    ['', '', ''],
    ['', '', ''],
    ['', '', '']
]
var isX = true
var gameOn = true
var boxesLeftToClick = Math.pow(board[0].length, 2)
function play(i, j) {
    //Znam da ne bi trebalo isX/board da gadjam globalno
    //ali mislim da je neprakticno da svaki put
    //unosim naizmenicno true/false da se zna
    //ko igra.
    if (board[i][j] != '')
        console.log('Ovo polje je vec zauzeto.')
    else {
        if (isX) {
            board[i][j] = 'x'
        }
        else {
            board[i][j] = 'o'
        }
        boxesLeftToClick--
        checkWinner(board, isX, gameOn)
        isX = !isX
        if(boxesLeftToClick == 0 && gameOn == true) {
            resetGame()
        }
        console.log(board)
    }
}
function checkWinner(board, isX, gameOn) {
    if (checkRow(board, 0)) {
        console.log('First row. Winner: ', isX ? 'x.' : 'o.')
     }
    else if (checkRow(board, 1)) {
        console.log('Second row. Winner: ', isX ? 'x.' : 'o.') }
    else if (checkRow(board, 2)) {
        console.log('Third row. Winner: ', isX ? 'x.' : 'o.') }
    else if (checkRow(transposeMatrix(board), 0)) {
        console.log('First column. Winner: ', isX ? 'x.' : 'o.') }
    else if (checkRow(transposeMatrix(board), 1)) {
        console.log('Second column. Winner: ', isX ? 'x.' : 'o.') }
    else if (checkRow(transposeMatrix(board), 2)) {
        console.log('Third column. Winner: ', isX ? 'x.' : 'o.') }
    else if (checkMainDiagonal(board)) {
        console.log('Main diagonal. Winner: ', isX ? 'x.' : 'o.' ) }
    else if (checkOtherDiagonal(board)) {
        console.log('The other diagonal. Winner: ', isX ? 'x.' : 'o.' ) }
}

function checkRow(board, i) {
    var gameOver = board[i][0] != '' && board[i][0] == board[i][1] && board[i][1] == board[i][2]
    if(gameOver) {
      resetGame()
    }
    return gameOver
}
function checkMainDiagonal(board) {
    var gameOver = board[0][0] != '' && board[0][0] == board[1][1] && board[1][1] == board[2][2]
    if(gameOver) {
        resetGame()
    }
    return gameOver
}
function checkOtherDiagonal(board) {
    var gameOver = board[0][2] != '' && board[0][2] == board[1][1] && board[1][1] == board[2][0]
    if(gameOver) {
        resetGame()
    }
    return gameOver
}
function transposeMatrix(matrix) {
  var result = new Array(matrix[0].length)
  for(var i = 0; i < result.length; i++) {
      result[i] = new Array(matrix[0].length)
      for(var j = 0; j < result[i].length; j++) {
          result[i][j] = matrix[j][i]
      }
  }
  return result
}

function resetGame() {
  console.log('Mozete otpoceti novu igru.')
  if(boxesLeftToClick == 0) {
      console.log('Neresno.')
    }
  this.board = emptyBoard
  this.gameOn = false
  this.isX = true

}