gistfile1.txt

// create a method that determines a winner from a given board. Manipulting matrix datasets.

var board = [
  ['x','x', 'o'],
  ['x', 'o', 'x'],
  ['x',null, null],
];
var board2 = [
  ['o', null, 'o'],
  ['x', 'x', 'x'],
  ['o',null, null],
];
var board3 = [
  ['o',null, 'o'],
  ['o', 'x', 'x'],
  ['o',null, null],
];
var board4 = [
  ['o',null, 's'],
  ['x', 'o', 's'],
  ['o',null, 's'],
];

var board5 = [
  ['x',null, 'o'],
  ['o', 'x', 'x'],
  ['o',null, 'x'],
];


function isWinner(board) {
  var winner = true;
  for(var grid = 0; grid < board.length; grid++) {
    /** checks horizontal matches **/
    for(var row = 0; row < board.length; row++){
        if(!board[grid][row] || board[grid][row] !== board[grid][0]){
          winner = false;
        }
        if (winner && row === board.length-1) return board[grid][0];
    }    
    winner = true; // find a better way to reset winner state?
    
    /** checks vertical matches **/
    for(var col = 0; col < board.length; col++){
      if(!board[col][grid] || board[col][grid] !== board[0][grid]){
          winner = false;
        }      
      if (winner && col === board.length-1) return board[col][grid];
    }
    winner = true;
    
    /** checks diagonal matches from right to left **/
    for(var d = board.length -1; d >= 0; d--){
      if(!board[grid][board.length-1] || !board[board.length-1][grid] || board[grid][board.length-1] === board[board.length-1][grid]){
          winner = false;
        }
      if (winner && grid === board.length-1) return board[grid][board.length-1];
    }
    winner = true;
    
    /** checks diagonal matches from left to right [IMPORTANT - the placement was critical]**/
    if(!board[grid][grid] || board[grid][grid] !== board[0][0]) {
      winner = false
    }
    if (winner && grid === board.length-1) {
      return board[grid][grid];
    }
    winner = true;
    
  }
  return 'No winner';
}

console.log('board '+isWinner(board))
console.log('board2 '+isWinner(board2))
console.log('board3 '+isWinner(board3))
console.log('board4 '+isWinner(board4))
console.log('board5 '+isWinner(board5))