Tic-Tac-Toe

make a html document name index.html here is the code for it

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Tic-Tac-Toe</title>
    <link rel="stylesheet" href="Style.css">
    <script src="Script.js"></script>
</head>
<body>
    <h1> Tic-Tak-Toe</h1>
    <hr>
    <br>
    <!-- 3X3-->
    <div id="board"></div>
</body>
</html>

Next you will mack a style sheet with css This is the code for this page.

body {
    font-family: Arial, Helvetica, sans-serif;
    text-align: center;
}

hr {
    width: 500px;
    height: 2px;
    background-color: black;
}


#board {
    width: 450px;
    height: 450px;
    /* background-color: gray; */
    margin: 0 auto;
    display: flex;
    flex-wrap: wrap;
}

.tile {
    width: 147px;
    height: 147px;

    /* Text */
    font-size: 150px;
    display: flex;
    justify-content: center; 
    align-items: center;    
}

.winner {
    background-color: lightgray;
    color: red;
}


.horizontal-line {
    border-bottom: 3px solid black;
}

.vertical-line {
    border-right: 3px solid black;
}

now we will finish it with Javascript

var board;
var playerO = "O";
var playerX = "X";
var currPlayer = playerO;
var gameOver = false;

window.onload = function() {
    setGame();
}

function setGame() {
    board = [
                [' ', ' ', ' '],
                [' ', ' ', ' '],
                [' ', ' ', ' ']
            ]

    for (let r = 0; r < 3; r++) {
        for (let c = 0; c < 3; c++) {
            let tile = document.createElement("div");
            tile.id = r.toString() + "-" + c.toString();
            tile.classList.add("tile");
            if (r == 0 || r == 1) {
                tile.classList.add("horizontal-line");
            }
            if (c == 0 || c == 1) {
                tile.classList.add("vertical-line");
            }
            tile.innerText = "";
            tile.addEventListener("click", setTile);
            document.getElementById("board").appendChild(tile);
        }
    }
}

function setTile() {
    if (gameOver) {
        return;
    }

    let coords = this.id.split("-");    //ex) "1-2" -> ["1", "2'"]
    let r = parseInt(coords[0]);
    let c = parseInt(coords[1]);

    if (board[r][c] != ' ') { 
        //already taken spot
        return;
    }

    board[r][c] = currPlayer; //mark the board
    this.innerText = currPlayer; //mark the board on html

    //change players
    if (currPlayer == playerO) {
        currPlayer = playerX;
    }
    else {
        currPlayer = playerO;
    }

    //check winner
    checkWinner();
}


function checkWinner() {
    //horizontally, check 3 rows
    for (let r = 0; r < 3; r++) {
        if (board[r][0] == board[r][1] && board[r][1] == board[r][2] && board[r][0] != ' ') {
            //if we found the winning row
            //apply the winner style to that row
            for (let i = 0; i < 3; i++) {
                let tile = document.getElementById(r.toString() + "-" + i.toString());
                tile.classList.add("winner");
            }
            gameOver = true;
            return;
        }
    }

    //vertically, check 3 columns
    for (let c = 0; c < 3; c++) {
        if (board[0][c] == board[1][c] && board[1][c] ==  board[2][c] && board[0][c] != ' ') {
            //if we found the winning col
            //apply the winner style to that col
            for (let i = 0; i < 3; i++) {
                let tile = document.getElementById(i.toString() + "-" + c.toString());                
                tile.classList.add("winner");
            }
            gameOver = true;
            return;
        }
    }

    //diagonally
    if (board[0][0] == board[1][1] && board[1][1] == board[2][2] && board[0][0] != ' ') {
        for (let i = 0; i < 3; i++) {
            let tile = document.getElementById(i.toString() + "-" + i.toString());                
            tile.classList.add("winner");
        }
        gameOver = true;
        return;
    }

    //anti-diagonally
    if (board[0][2] == board[1][1] && board[1][1] == board[2][0] && board[0][2] != ' ') {
        //0-2
        let tile = document.getElementById("0-2");                
        tile.classList.add("winner");

        //1-1
        tile = document.getElementById("1-1");                
        tile.classList.add("winner");

        //2-0
        tile = document.getElementById("2-0");                
        tile.classList.add("winner");
        gameOver = true;
        return;
    }
}