JQuery Tic Tac Toe

A simple tic-tac-toe game, using JQuery.

by Kleofáš Hatlapatka

HTML

<div id="tictactoe"></div>

JavaScript

/*
 * A complete tic-tac-toe widget, using JQuery.  Just include this 
 * script in a browser page and play.  A tic-tac-toe game will be 
 * included as a child element of the element with id "tictactoe".  
 * If the page has no such element, it will just be added at the end 
 * of the body.
 */
$(function () {

    var squares = [], 
        SIZE = 3,
        EMPTY = "&nbsp;",
        score,
        moves,
        turn = "X",

    /*
     * To determine a win condition, each square is "tagged" from left
     * to right, top to bottom, with successive powers of 2.  Each cell
     * thus represents an individual bit in a 9-bit string, and a
     * player's squares at any given time can be represented as a
     * unique 9-bit value. A winner can thus be easily determined by
     * checking whether the player's current 9 bits have covered any
     * of the eight "three-in-a-row" combinations.
     *
     *     273                 84
     *        \               /
     *          1 |   2 |   4  = 7
     *       -----+-----+-----
     *          8 |  16 |  32  = 56
     *       -----+-----+-----
     *         64 | 128 | 256  = 448
     *       =================
     *         73   146   292
     *
     */
    wins = [7, 56, 448, 73, 146, 292, 273, 84],

    /*
     * Clears the score and move count, erases the board, and makes it
     * X's turn.
     */
    startNewGame = function () {
        turn = "X";
        score = {"X": 0, "O": 0};
        moves = 0;
        squares.forEach(function (square) {square.html(EMPTY);});
    },

    /*
     * Returns whether the given score is a winning score.
     */
    win = function (score) {
        for (var i = 0; i < wins.length; i += 1) {
            if ((wins[i] & score) === wins[i]) {
                return true;
            }
        }
        return false;
    },

    /*
     * Sets the clicked-on square to the current player's mark,
     * then checks for a win or cats game.  Also changes the
     * current player.
  ...