boardPossibleWins

var getCurrentRow = function(board, row, col) {
  return board[row];
};

var getCurrentCol = function(board, row, col) {
  var flatCol = [];
  board.forEach(function(row) {
    flatCol.push(row[col]);
    return row;
  });
  return flatCol;
};

var getDiagonal = function(board, row, col) {
  var flatDiagonal = [];
  if(row === col) {
    board.forEach(function(rowArr, i) {
      flatDiagonal.push(rowArr[i]);
    });
  } else {
    board.forEach(function(rowArr, i) {
      flatDiagonal.push(rowArr[rowArr.length - 1- i]);
    });
  }
  return flatDiagonal;
};

var isInDiagonalPath = function(row, col) {
  if((row === 0 && (col === 0 || col === 2)) || 
     (row === 1 && col === 1) || 
     (row === 2 && (col === 0 || col === 2))) {
    return true;
  } else {
    return false;
  }
};

var winsWithThisSpace = function(board, row, col, marker=undefined) {
  var currentRow = getCurrentRow(board, row, col);
  var currentCol = getCurrentCol(board, row, col);
  var diagonalArr, minorDiagonalArr;
  if(isInDiagonalPath(row, col)) {
    diagonalArr = getDiagonal(board, row, col);
    if(row === 1 && col === 1) {
      minorDiagonalArr = getDiagonal(board, 0, 2);
    }
  }
  var arrayHolder = [currentRow, currentCol, diagonalArr, minorDiagonalArr];
  var wins = 0;
  var count;
  arrayHolder.forEach(function(array) {
    count = 0;
    if(Array.isArray(array)) {
      array.forEach(function(element) {
        if(element === '-' || element === marker) {
         count++;
        }
      });
      if(count === 3) {
        wins++;
      }
    }
  });
  return wins;
};

var boardPossibleWins = function(board, marker='X') {
  var boardChances = [];
  var chanceRow;
  board.forEach(function(row, rowIndex) {
    chanceRow = [];
    row.forEach(function(col, colIndex) {
      chanceRow.push(winsWithThisSpace(board, rowIndex, colIndex, marker));
      return col;
    });
    boardChances.push(chanceRow);
    return row;
  });
  return boardChances;
};

var board = [['-','X','-'],
             ['-','-','O'],
             ['-','-','X']];

var xChances = boardPossibleWins(board, 'X');
var oChances = boardPossibleWins(board, 'O');
oChances;