Skip to content

Instantly share code, notes, and snippets.

@bagaag

bagaag/tic-tac-toe.html

Last active March 2, 2017 13:00
Show Gist options
  • Save bagaag/9458565 to your computer and use it in GitHub Desktop.
Save bagaag/9458565 to your computer and use it in GitHub Desktop.
Download ZIP
Single File Tic Tac Toe against the Computer
Raw
tic-tac-toe.html
<!DOCTYPE html>
<!--
Single file Tic Tac Toe against the Computer
https://gist.github.com/wiseley/9458565/
Author: Matt Wiseley
License: GPL - http://www.gnu.org/licenses/gpl.html
-->
<html>
<head>
<meta charset="UTF-8">
<style>
body { font-family: arial; font-size: 1.2em; }
#board {
width: 306px;
height: 306px;
border: 1px solid #ccc;
}
#board div {
float: left;
height: 100px;
width: 100px;
border: 1px solid #aaa;
text-align: center;
color: #ddd;
}
#board div span {
font-family: arial;
font-size: 70px;
margin-top: 10px;
color: black;
display: block;
}
.winner { background-color: lightgreen; }
#status { font-size: 1.2em; font-weight: bold; }
</style>
<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script>
var computer = 'O'; // the computer is X
var player = 'X'; // you are O
var turn = player; // the player goes first
var xwins = 0, owins = 0; // win tallies
var turns = 0;
/* =============================== */
/* GAME BOARD NAVIGATION FUNCTIONS */
// test each cell in each row with a function and return the index of
// the first whose values causes the function to return true;
// return -1 if no row returns true
function iterateCols(func) {
return findInGrid(true, func);
}
function iterateRows(func) {
return findInGrid(false, func);
}
function findInGrid(isRow, func) {
for (var i=0; i<3; i++) {
var a = isRow ? val(i,0) : val(0,i);
var b = isRow ? val(i,1) : val(1,i);
var c = isRow ? val(i,2) : val(2,i);
if (func(a,b,c,i)) return i;
}
return -1;
}
// returns 0 if diag starting at 0,0 matches, 2 if starting at 2,0 matches, else -1
function iterateDiags(func) {
if (func(val(0,0), val(1,1), val(2,2),0)) return 0;
else if (func(val(2,0), val(1,1), val(0,2),2)) return 2;
else return -1;
}
// from top, left to right diag is 0, right to left is 2.
// convert the [a,b,c] index of the diagonal based which way its going
function convertDiag(iterateVal, ix) {
//These: 00 01 02 20 21 22
//become: 00 11 22 20 11 02
if (iterateVal==0) {
if (ix==0) return [0,0];
if (ix==1) return [1,1];
if (ix==2) return [2,2];
}
else {
if (ix==0) return [2,0];
if (ix==1) return [1,1];
if (ix==2) return [0,2];
}
}
// get the value of the square at x,y coords
function val(x,y,newVal) {
if (typeof newVal == 'undefined') {
return $("#s"+x+""+y+" span").text();
}
else {
$("#s"+x+""+y).html("<span>"+newVal+"</span>");
}
}
/* =================== */
/* GAME PLAY FUNCTIONS */
function init() {
// register event handler for player turns
$(document).ready(function() {
$("#board div").click(function() {
if (turn==player) {
if (!$(this).find("span").length>0) {
$(this).html("<span>"+player+"</span>");
processTurn();
}
}
});
});
}
// check the puzzle for a win and swap turns
function processTurn() {
turns++;
// winner requires 3 in a row of same value with no blanks
var winnerTest = function(a,b,c) {
return a==b & a==c && a!='';
};
// check straight across
var y = iterateCols(winnerTest);
if (y > -1) {
finish(val(y,0), [[y,0],[y,1],[y,2]]);
return;
}
// check up and down
var x = iterateRows(winnerTest);
if (x > -1) {
finish(val(0,x), [[0,x],[1,x],[2,x]]);
return;
}
// check diagonals
var d = iterateDiags(winnerTest);
if (d == 0) {
finish(val(0,0), [[0,0],[1,1],[2,2]]);
return;
}
else if (d == 2) {
finish(val(2,0), [[2,0],[1,1],[0,2]]);
return;
}
// if there are no blanks, finish with a draw
if (iterateCols(function(a,b,c) { return a=='' || b=='' || c==''; }) == -1) {
finish();
}
// otherwise proceed to the next turn
else {
if (turn==computer) {
turn = player;
}
else if (turn==player) {
turn = computer;
computerTurn();
processTurn();
}
// else: the game is over, do nothing
}
}
// looks for an imminent opponent win and prevents it
function strategyAvertLoss() {
var isPlayer = function(val) { return val==player; }
var isBlank = function(val) { return val==''; }
var findImminentLoss = function(a,b,c,i){
if (matches([a,b,c], isPlayer)==2 && matches([a,b,c], isBlank)==1) {
ret = findInArray([a,b,c], isBlank);
return true;
} else return false;
};
var ret = -1;
var ix = -1;
// search rows
ix = iterateRows(findImminentLoss);
if (ix>-1 && ret>-1) return [ret, ix];
// search columns
ix = iterateCols(findImminentLoss);
if (ix>-1 && ret>-1) return [ix, ret];
// search diagonals
ix = iterateDiags(findImminentLoss);
if (ix>-1 && ret>-1) return convertDiag(ix, ret);
else return false;
}
// take the middle if its available
function strategyMiddle() {
if (val(1,1)=='') return [1,1];
else return false;
}
// take a corner if the middle was taken first turn
function strategyMiddleDefense() {
// if middle is taken, take the first corner
if (turns==1 && val(1,1)==player) return [0,0];
if (turns==3 && val(1,1)==player) {
if (val(2,0)=='') return [2,0];
if (val(0,2)=='') return [0,2];
if (val(2,2)=='') return [2,2];
}
return false;
}
// defense against the corner strategy
function strategyCornerDefense() {
if (val(0,1)==player && val(1,0)==player && val(0,0)=='') return [0,0];
if (val(0,1)==player && val(1,2)==player && val(0,2)=='') return [0,2];
if (val(1,2)==player && val(2,1)==player && val(2,2)=='') return [2,2];
if (val(2,1)==player && val(1,0)==player && val(2,0)=='') return [2,0];
return false;
}
// looks for a rol/col/diag that poses
// an opportunity for a win or nearest win
function strategyBestOpportunity() {
var ix = -1, y = -1, x = -1, d = -1;
var count = 0, countY = 0, countX = 0, countD = 0;
// look for the best opportunity, to be passed to iterateRows/Cols
var seekOpportunity = function(a,b,c,i){
var match = 0;
var opponent = 0;
var blank = 0;
if (a==computer) match++; else if (a==player) opponent++; else if (a=='') blank++;
if (b==computer) match++; else if (b==player) opponent++; else if (b=='') blank++;
if (c==computer) match++; else if (c==player) opponent++; else if (c=='') blank++;
if (match>0 && match<3 && opponent==0) {
if (match > count) {
count = match;
ix = i;
}
}
};
// get the best row
iterateRows(seekOpportunity);
countY = count;
y = ix;
ix = -1; count = 0;
// get the best column
iterateCols(seekOpportunity);
countX = count;
x = ix;
ix = -1; count = 0;
// get the best diagonal
iterateDiags(seekOpportunity);
countD = count;
d = ix;
ix = -1; count = 0;
// determine the winning strategy (col, row or diag)
var turnX = -1, turnY = -1;
if (countX >= countY && countX >= countD) {
turnX = x;
turnY = findInArray([val(x,0), val(x,1), val(x,2)],
function(v) { if (v=='') return true; }
);
}
else if (countY >= countX && countY >= countD) {
turnY = y;
turnX = findInArray([val(0,y), val(1,y), val(2,y)],
function(v) { if (v=='') return true; }
);
}
else if (countD >= countX && countD >= countY) {
if (val(1,1)=='') {turnX = 1; turnY = 1;}
else if (d == 0) {
if (val(0,0)=='') {turnX = 0; turnY = 0;}
else {turnX = 2; turnY = 2;}
}
else {
if (val(2,0)=='') {turnX = 2; turnY = 0;}
else {turnX = 0; turnY = 2;}
}
}
if (turnX==-1 || turnY==-1) return false;
else return [turnX,turnY];
}
// take the win if it is available
function strategyWin() {
var isComputer = function(val) { return val==computer; }
var isBlank = function(val) { return val==''; }
// look for 2 computer plays and one blank, indicating an immediate win
var canWin = function(a,b,c) {
if (matches([a,b,c], isComputer)==2 &&
matches([a,b,c], isBlank)==1) {
ret = findInArray([a,b,c], isBlank);
return true;
}
};
var ret = -1;
var ix = -1;
// search rows
ix = iterateRows(canWin);
if (ix>-1 && ret>-1) return [ret, ix];
// search columns
ix = iterateCols(canWin);
if (ix>-1 && ret>-1) return [ix, ret];
// search diagonals
ix = iterateDiags(canWin);
if (ix>-1 && ret>-1) return convertDiag(ix, ret);
else return false;
}
// go in a randomly selected blank space
function strategyRandom() {
// gather all the blank spots in an array
var blanks = [];
for (var x=0; x<3; x++) {
for (var y=0; y<3; y++) {
if (val(x,y)=='') blanks.push([x,y]);
}
}
// return a random entry in the array of blanks
if (blanks.length>0) {
var r = Math.floor((Math.random()*blanks.length));
return blanks[r];
}
else return false;
}
// no strategy - just take the first blank space
function strategySequential() {
// just take the first available space
for (var x=0; x<3; x++) {
for (var y=0; y<3; y++) {
if (val(x,y)=='') return [x,y];
}
}
return false;
}
// computer takes its turn
function computerTurn() {
var strategies = [];
if (option('win')) strategies.push(strategyWin);
if (option('avertLoss')) strategies.push(strategyAvertLoss);
if (option('middleDefense')) strategies.push(strategyMiddleDefense);
if (option('middle')) strategies.push(strategyMiddle);
if (option('cornerDefense')) strategies.push(strategyCornerDefense);
if (option('bestOpportunity')) strategies.push(strategyBestOpportunity);
if (option('random')) strategies.push(strategyRandom);
if (option('sequential')) strategies.push(strategySequential);
for (var i=0; i<strategies.length; i++) {
var turn = strategies[i]();
if (!turn) continue;
console.log(i,turn);
val(turn[0], turn[1], computer);
break;
}
}
// highlight the square at x,y coords, a: [[x,y],..]
function highlightWinner(a) {
for (var i=0; i<a.length; i++) {
var coord = a[i];
var x = coord[0], y = coord[1];
var sel = "#s"+''+x+''+y;
$(sel).addClass('winner');
}
}
// finish the game
function finish(p, highlight) {
if (typeof p != 'undefined') {
$("#status").text(p + ' is the winner!');
}
else {
$("#status").text('The game ended with a draw.');
}
turn = '';
if (typeof highlight != 'undefined') {
highlightWinner(highlight);
}
if (p=='X') xwins++;
else if (p=='O') owins++;
$("#xwins").text(xwins);
$("#owins").text(owins);
}
// new game
function newGame() {
$("#board div").find("span").remove();
$(".winner").removeClass("winner");
turn = player;
$("#status").empty();
turns = 0;
}
/* ================= */
/* UTILITY FUNCTIONS */
// gets checkbox option true/false status
function option(name) {
return $("input[name='"+name+"']")[0].checked;
}
// returns the count of matching array members
function matches(a, func) {
var c = 0;
for (var i=0; i<a.length; i++) {
if (func(a[i])) c++;
}
return c;
}
// returns first index of matching value in array, or -1
function findInArray(a, func) {
for (var i=0; i<a.length; i++) {
if (func(a[i])) return i;
}
return -1;
}
init();
</script>
</head>
<body>
<h1>Tic Tac Toe</h1>
<div id="board">
<div id="s00"></div>
<div id="s10"></div>
<div id="s20"></div>
<div id="s01"></div>
<div id="s11"></div>
<div id="s21"></div>
<div id="s02"></div>
<div id="s12"></div>
<div id="s22"></div>
</div>
<p id="status"></p>
<p>X wins: <span id="xwins">0</span><br/>
O wins: <span id="owins">0</span></p>
<p><button onclick="newGame()">New Game</button></p>
<p>
Strategies:<br/>
<label><input type="checkbox" name="win" val="1" checked/> Win</label><br/>
<label><input type="checkbox" name="avertLoss" val="1" checked/> Avert Loss</label><br/>
<label><input type="checkbox" name="middleDefense" val="1" checked/> Middle Defense</label><br/>
<label><input type="checkbox" name="middle" val="1" checked/> Middle</label><br/>
<label><input type="checkbox" name="cornerDefense" val="1" checked/> Corner Defense</label><br/>
<label><input type="checkbox" name="bestOpportunity" val="1" checked/> Best Opportunity</label><br/>
<label><input type="checkbox" name="random" value="1" checked/> Random</label><br/>
<label><input type="checkbox" name="sequential" val="1"/> Sequential</label><br/>
</p>
</body>
</html>
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment