Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Auto Save

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                
              
            
!

CSS

              
                
              
            
!

JS

              
                /*

                                   O |   | X
                                   ---------
                                   X |   | X
                                   ---------
                                     | O | O

                             //       ||        \\

                O | X | X          O |   | X        O |   | X
                ---------          ---------        ---------
                X |   | X          X | X | X        X |   | X
                ---------          ---------        ---------
                  | O | O            | O | O        X | O | O

              //          \\                     //          \\

        O | X | X          O | X | X        O | O | X       O |   | X
        ---------          ---------        ---------       ---------
        X | O | X          X |   | X        X |   | X       X | O | X
        ---------          ---------        ---------       ---------
          | O | O          O | O | O        X | O | O       X | O | O

                                        //

                                   O | O | X
                                   ---------
                                   X | X | X
                                   ---------
                                   O | O | O

*/
// this is the board flattened and filled with some values to easier asses the Artificial Inteligence.
var origBoard = ["O",1 ,"X","X",4 ,"X", 6 ,"O","O"];

// human
var huPlayer = "O";
// ai
var aiPlayer = "X";


// keep track of function calls
var fc = 0;

// finding the ultimate play on the game that favors the computer
var bestSpot = minimax(origBoard, aiPlayer);

//loging the results
console.log("index: " + bestSpot.index);
console.log("function calls: " + fc);

// the main minimax function
function minimax(newBoard, player){
  
  //keep track of function calls;
  fc++;

  //available spots
  var availSpots = emptyIndexies(newBoard);

  // checks for the terminal states such as win, lose, and tie and returning a value accordingly
  if (winning(newBoard, huPlayer)){
     return {score:-10};
  }
	else if (winning(newBoard, aiPlayer)){
    return {score:10};
	}
  else if (availSpots.length === 0){
  	return {score:0};
  }

// an array to collect all the objects
  var moves = [];

  // loop through available spots
  for (var i = 0; i < availSpots.length; i++){
    //create an object for each and store the index of that spot that was stored as a number in the object's index key
    var move = {};
  	move.index = newBoard[availSpots[i]];

    // set the empty spot to the current player
    newBoard[availSpots[i]] = player;

    //if collect the score resulted from calling minimax on the opponent of the current player
    if (player == aiPlayer){
      var result = minimax(newBoard, huPlayer);
      move.score = result.score;
    }
    else{
      var result = minimax(newBoard, aiPlayer);
      move.score = result.score;
    }

    //reset the spot to empty
    newBoard[availSpots[i]] = move.index;

    // push the object to the array
    moves.push(move);
  }

// if it is the computer's turn loop over the moves and choose the move with the highest score
  var bestMove;
  if(player === aiPlayer){
    var bestScore = -10000;
    for(var i = 0; i < moves.length; i++){
      if(moves[i].score > bestScore){
        bestScore = moves[i].score;
        bestMove = i;
      }
    }
  }else{

// else loop over the moves and choose the move with the lowest score
    var bestScore = 10000;
    for(var i = 0; i < moves.length; i++){
      if(moves[i].score < bestScore){
        bestScore = moves[i].score;
        bestMove = i;
      }
    }
  }

// return the chosen move (object) from the array to the higher depth
  return moves[bestMove];
}

// returns the available spots on the board
function emptyIndexies(board){
  return  board.filter(s => s != "O" && s != "X");
}

// winning combinations using the board indexies for instace the first win could be 3 xes in a row
function winning(board, player){
 if (
        (board[0] == player && board[1] == player && board[2] == player) ||
        (board[3] == player && board[4] == player && board[5] == player) ||
        (board[6] == player && board[7] == player && board[8] == player) ||
        (board[0] == player && board[3] == player && board[6] == player) ||
        (board[1] == player && board[4] == player && board[7] == player) ||
        (board[2] == player && board[5] == player && board[8] == player) ||
        (board[0] == player && board[4] == player && board[8] == player) ||
        (board[2] == player && board[4] == player && board[6] == player)
        ) {
        return true;
    } else {
        return false;
    }
}

              
            
!
999px

Console