Tic Tac Toe

This is an npm module that can be used for Free Code Camp's Tic Tac Toe project. It features three different game types:

• two player game
• easy one player game
• unbeatable one player game

It uses a simple API that you can easily plug into your application.

Install

$ npm install tictactoe-freecodecamp

Include TicTacToe into Your Project

NOTE: This library is now only compatible with ES6 modules as it is intended as a front end library.

import ticTacToe from 'tictactoe-freecodecamp';

Tic Tac Toe Games

When you require or import the tic tac toe module into your project, you'll have access to three different game types.

To access a two player game:

const twoPlayerGame = ticTacToe.twoPlayerGame();

To access an easy one player game, in which the automated player will be a simple automated player:

const easyGame = ticTacToe.easyGame();

To access an unbeatable one player game, in which the automated player will be an unbeatable automated player:

const unbeatableGame = ticTacToe.unbeatableGame();

When playing an automated game, you can choose whether the human player will be 'x' or 'o' by including the player symbol of choice as an argument:

const easyGameAsO = ticTacToe.easyGame('o');

or:

const easyGameAsX = ticTacToe.easyGame('x');

As shown in earlier examples, if no argument is included, the human player will default to 'x'.

Using the game

You can get the state of the game at anytime with the getState() method. For example, every game automatically sets the current player to 'x.'

const twoPlayerGame = ticTacToe.twoPlayerGame();
twoPlayerGame.getState();
// 'Current player is x'

If you simply want to access just the current player, use the getCurrentPlayer method:

const twoPlayerGame = ticTacToe.twoPlayerGame();
twoPlayerGame.getCurrentPlayer();
// 'x'

You can set the current player with the setCurrentPlayer method:

const twoPlayerGame = ticTacToe.twoPlayerGame();
twoPlayerGame.setCurrentPlayer('o');
twoPlayerGame.getCurrentPlayer();
// 'o'

The Tic Tac Toe board is represented in this module as a two-dimensional array. Each empty space is represented by a null object, and occupied spaces are represented with either simple 'x' or 'o' strings. The board always starts empty. To get the current state of the board, call the getBoardSpaces method:

twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, null, null],
//      [null, null, null]
//  ]

Playing the game: Two players

To play the game just make a call to the turn method. If it is a human player's turn, include the row index and column index of the space you'd like to add the move as its arguments.

column >  0     1     2
        [null, null, null]   0
        [null, null, null]   1
        [null, null, null]   2
                             ^ row

Example:

const twoPlayerGame = ticTacToe.twoPlayerGame();
twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, null, null],
//      [null, null, null]
//  ]

// make move in center square: row 1, column 1
twoPlayerGame.turn(1,1);
twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'x' , null],
//      [null, null, null]
//  ]

The turn method will always make the move of the current player, and then switch the current player to the next player. So no need to keep track of which letter should be used: we've got that covered.

twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'x' , null],
//      [null, null, null]
//  ]
twoPlayerGame.turn(2,2);
twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'x ', null],
//      [null, null, 'o' ]
//  ]

To check if the game is over, you can use the isGameOver method:

twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'x' , null],
//      [null, null, 'o' ]
//  ]
twoPlayerGame.isGameOver();
// false

After a completed game, you can make a call to getState, which will return either 'Draw' (if the game ends in a draw) or tell you who the winner is. Example:

twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, 'x' ],
//      [null, 'x' , 'o' ],
//      [null, null, 'o' ]
//  ]
twoPlayerGame.turn(2,0);
twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, 'x' ],
//      [null, 'x' , 'o' ],
//      ['x' , null, 'o' ]
//  ]
twoPlayerGame.isGameOver();
// true
twoPlayerGame.getState();
// 'x is the winner'

or:

twoPlayerGame.getBoardSpaces();
//  [
//      ['x' , 'o' , 'o' ],
//      ['o' , 'x' , 'x' ],
//      [null, 'x' , 'o' ]
//  ]
twoPlayerGame.turn(2,0);
twoPlayerGame.getBoardSpaces();
//  [
//      ['x' , 'o' , 'o' ],
//      ['o' , 'x' , 'x' ],
//      ['x' , 'x' , 'o' ]
//  ]
twoPlayerGame.isGameOver();
// true
twoPlayerGame.getState();
// 'Draw'

To restart the game, use the restart method, which resets the board to empty and current player to 'x'.

twoPlayerGame.getBoardSpaces();
//  [
//      ['x' , 'o' , 'o' ],
//      ['o' , 'x' , 'x' ],
//      ['x' , 'x' , 'o' ]
//  ]
twoPlayerGame.restart();
twoPlayerGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, null, null],
//      [null, null, null]
//  ]
twoPlayerGame.getCurrentPlayer();
// 'x'

Playing the game: One player

You can also choose to play against an automated player. The 'easy' player will choose a random available space when taking a turn. The 'x' player will always go first by default, which (if no player symbol is included as an argument when intially creating the game type) will be the human player:

const easyGame = ticTacToe.easyGame();
easyGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, null, null],
//      [null, null, null]
//  ]
easyGame.turn(1,1);
easyGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'x' , null],
//      [null, null, null]
//  ]
easyGame.turn();
// 'o' player makes random move from available spaces
easyGame.getBoardSpaces();
//  [
//      [null, 'o' , null],
//      [null, 'x' , null],
//      [null, null, null]
//  ]

As you can see, you do not provide arguments when using an automated player. You just call the turn method, and it automatically makes a move. The same goes when using an unbeatable player. The only difference is, the unbeatable player will make moves to block you or try to win.

const unbeatableGame = ticTacToe.unbeatableGame();
unbeatableGame.turn(1,1);
unbeatableGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, null, null],
//      [null, null, 'x' ]
//  ]
unbeatableGame.turn();
// unbeatable 'o' player will make the best move it can, like
// always taking the center space if available
unbeatableGame.getBoardSpaces();
//  [
//      [null, null, null],
//      [null, 'o' , null],
//      [null, null, 'x' ]
//  ]

// ... later in the game...

unbeatableGame.getBoardSpaces();
//  [
//      [null, null, 'o' ],
//      [null, 'o' , 'x' ],
//      ['x' , null, 'x' ]
//  ]
unbeatableGame.turn();
// unbeatable 'o' player will always make blocking move
unbeatableGame.getBoardSpaces();
//  [
//      [null, null, 'o' ],
//      [null, 'o' , 'x' ],
//      ['x' , 'o' , 'x' ]
//  ]

// ... and if you make a mistake...

unbeatableGame.turn(1,0);
unbeatableGame.getBoardSpaces();
//  [
//      [null, null, 'o' ],
//      ['x' , 'o' , 'x' ],
//      ['x' , 'o' , 'x' ]
//  ]
unbeatableGame.turn();
// unbeatable 'o' player will take advantage of your mistake
unbeatableGame.getBoardSpaces();
//  [
//      [null, 'o' , 'o' ],
//      ['x' , 'o' , 'x' ],
//      ['x' , 'o' , 'x' ]
//  ]
unbeatableGame.getState();
// o is the winner

The best you could possibly do is end in a draw with the unbeatable player.

Helpful methods

There are several methods included in this module that are helpful when building your Tic Tac Toe applications. For example, to check if a particular space is occupied, use isSpaceOccupied.

unbeatableGame.getBoardSpaces();
//  [
//      [null, null, 'o' ],
//      [null, 'o' , 'x' ],
//      ['x' , 'o' , 'x' ]
//  ]
unbeatableGame.isSpaceOccupied(0,0);
// false
unbeatableGame.isSpaceOccupied(1,1);
// true

You can also check if a particular move is valid given in any particular game state with the isValidMove method:

unbeatableGame.getBoardSpaces();
//  [
//      [null, null, 'o' ],
//      [null, 'o' , 'x' ],
//      ['x' , 'o' , 'x' ]
//  ]
unbeatableGame.isValidMove(1,0);
// true
unbeatableGame.isValidMove(0,2);
// false
unbeatableGame.isValidMove(0,3);
// false
unbeatableGame.isValidMove(2, 'bubble');
// false

Issues

If you find any issues or bugs with the game or want to request new features, please do so here.

Tests

$ npm test

License

The MIT License (MIT)

Copyright (c) 2017 Derek Shoemaker

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.