o's and x's compression function

Question

need to detect a diagonal win, have acheived this horizontally with the hScore part of the detwct win function but it can not detect a horizontal winner, ive tried to make the function so it uses the indexs of the arrays to trigger the win when each one has a o or x placed on it, but it doesnt work, is there a better way for me to achieve this ?

The game is o's and x's, with out the function working correctly it wont detect the winner for diagonal wins

 players = ['o', 'x'];
    currentPlayerIndex = 0;
    
    board = [
      [' ', ' ', ' '],
      [' ', ' ', ' '],
      [' ', ' ', ' '],
    ];
    
    
    
    play = (x, y) => {
      let message = 'current player wins';
      if (getSquare(x, y) === ' ') {
        setSquare(x, y, currentPlayer());
        document.getElementById('square' + x + y).innerHTML = currentPlayer();
        if (detectWinner()) {
          alert(currentPlayer() + message);
          console.log('winner');
        }
        changePlayer();
      }
    };
    
  detectWinner = () => {

for (let i = 0; i < board.length; i++) {
    let hScore = board[i];
    let dScore = [...board[i]];
    let hScoreString = JSON.stringify(hScore);
    
    console.log(board[i]);
    let matches = [
      JSON.stringify(['x', 'x', 'x']),
      JSON.stringify(['o', 'o', 'o']),
    ];

    if (matches.includes(hScoreString)) {
      return true;
    
    } else if ( dScore[(0, 0), (0, 1), (0, 1)].every()  === 'o'  )                {
      return true;
    }
   }
 return false;
   };

        
    currentPlayer = () => {
      console.log(players[currentPlayerIndex]);
      return players[currentPlayerIndex];
    };
    
    changePlayer = () => {
      currentPlayerIndex = (currentPlayerIndex + 1) % 2;
    };
    getSquare = (x, y) => {
      return board[x][y];
    };
    
    setSquare = (x, y, value) => {
      board[x][y] = value;
    };
    
    reset = () => {
      ////refresh page
    };

`cScore[i] === ['x', 'x', 'x'] || ['o', 'o', 'o']` This is not the correct way to check for 2 conditions. — takendarkk, Aug 04 '21 at 13:47
Arrays cannot be compared as single variables. Look at this: https://stackoverflow.com/questions/7837456/how-to-compare-arrays-in-javascript — AlexSp3, Aug 04 '21 at 13:48
i think it should be `cScore[i] === ['x', 'x', 'x'] || cScore[0] === ['o', 'o', 'o']` — Irfan wani, Aug 04 '21 at 13:48

score 1 · Accepted Answer · answered Aug 04 '21 at 13:58

You are getting the wrong return values because of the way you are comparing arrays and variables.

We have to first convert arrays to strings to compare them. We can use JSON.stringify to do so.

let cScoreString = JSON.stringify(cScore)
    
let matches = [
  JSON.stringify(["x", "x", "x"]),
  JSON.stringify(["o", "o", "o"])
]

Then we can check if our variable is found in the array.

if (matches.includes(cScoreString)) return true

or

if (matches[0] === cScoreString || matches[1] === cScoreString) return true

Full code:

let example = [
  ["x", "x", "o"],
  ["o", "o", "o"], // Winning line
  ["x", "o", "x"]
]

detectWinner = (board) => { 
  for (let i = 0; i < board.length; i++) {
    let cScore = board[i];
    let cScoreString = JSON.stringify(cScore)
    
    let matches = [
      JSON.stringify(["x", "x", "x"]),
      JSON.stringify(["o", "o", "o"])
    ]
    
    if (matches.includes(cScoreString)) return true
  }
  return false;
};

console.log(detectWinner(example))

this has worked thank you, could it be used to check diagonal conditions as well ? — dcode, Aug 04 '21 at 15:54
@dcode You'll have to take a different approach to check diagonal conditions, take a look at this article [Algorithm to detect a tic tac toe winner](https://jayeshkawli.ghost.io/tic-tac-toe/). — lejlun, Aug 04 '21 at 16:07

AlexSp3 · Answer 2 · 2021-08-04T14:08:58.677

In order to compare both arrays, you can use the every() function, which will return true if all elements of an array pass a condition.

detectWinner = () => {
 
  for (let i = 0; i < board.length; i++) {

    var cScore = [...board[i]];   // this is the correct way of copy an array into another variable

    for (let j = 0; j < cScore.length; j++) console.log(board[i][j]);

    console.log(cScore);

    // I would compare the array using the every function
    if (cScore[i].every(e => e === 'x') || cScore[i].every(e => e === 'o')) {
      return true;
    }
  }
  return false;
};

o's and x's compression function

2 Answers2