Building a Simple Tic-Tac-Toe Game with HTML, CSS, and JavaScript

Harsh Kothari - April 4, 2025

In this tutorial, we'll explore how to create a classic Tic-Tac-Toe game using only HTML, CSS, and JavaScript, without the need for any external assets. This game is a great introduction to basic web programming concepts such as handling user interactions, updating the DOM, and managing game logic.


Step 1: Setting Up the Project

Create a new folder for your project and inside it, create three files:

  • index.html — the main HTML document.
  • style.css — for styling the game.
  • script.js — to handle the game logic.


index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Tic-Tac-Toe Game</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <div id="gameBoard" class="game-board"></div>
    <script src="script.js"></script>
</body>
</html>


Step 2: Styling the Game

style.css

body {
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
    background-color: #f0f0f0;
}

.game-board {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    grid-template-rows: repeat(3, 100px);
    gap: 5px;
}

.cell {
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #fff;
    font-size: 2em;
    cursor: pointer;
    user-select: none;
}


Step 3: JavaScript for Game Logic

script.js

const gameBoard = document.getElementById('gameBoard');
let currentPlayer = 'X';
const gameState = Array(9).fill(null);

function checkWinner() {
    const winPatterns = [
        [0, 1, 2], [3, 4, 5], [6, 7, 8], // Rows
        [0, 3, 6], [1, 4, 7], [2, 5, 8], // Columns
        [0, 4, 8], [2, 4, 6] // Diagonals
    ];

    for (let pattern of winPatterns) {
        const [a, b, c] = pattern;
        if (gameState[a] && gameState[a] === gameState[b] && gameState[a] === gameState[c]) {
            return gameState[a];
        }
    }
    return null;
}

function cellClicked(e) {
    const idx = e.target.getAttribute('data-index');
    if (gameState[idx] || checkWinner()) {
        return;
    }
    gameState[idx] = currentPlayer;
    e.target.textContent = currentPlayer;
    currentPlayer = currentPlayer === 'X' ? 'O' : 'X';

    const winner = checkWinner();
    if (winner) {
        alert(`${winner} wins!`);
    } else if (!gameState.includes(null)) {
        alert("It's a draw!");
    }
}

function createBoard() {
    for (let i = 0; i < gameState.length; i++) {
        const cell = document.createElement('div');
        cell.classList.add('cell');
        cell.setAttribute('data-index', i);
        cell.addEventListener('click', cellClicked);
        gameBoard.appendChild(cell);
    }
}

createBoard();


Conclusion: Running Your Game

Now that the game is set up, open your index.html file in any modern web browser to start playing Tic-Tac-Toe. You should see a grid of 9 squares where two players can take turns clicking to place 'X' or 'O'. The game will check for a winner after each move and declare a winner or a draw.

This simple project introduces key programming concepts such as arrays, loops, and functions, and shows how they can be applied to create interactive web applications. Feel free to expand this game by adding features like player vs computer mode, score tracking, or stylish animations. Enjoy your development journey!



Bonus: Try your game here

https://www.thecodeground.in/ground/web/41c0a3a0-eedf-4647-94ad-23547a10fd14