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HTML 

              
                <div id="container">
	<div id="points">
		<p id="current-points">Points: 0</p>
		<p id="high-score">High score: 0</p>
	</div>
	<canvas id="room" width="250" height="250"></canvas>
	
	<p style="width: 250px">Use the arrow keys to move the snake. The blue square is food. The gray squares are obstacles - running into them ends the game.</p>
</div>
!

CSS 

              
                body {
    margin: 0;
    padding: 0;
}

p {
	pading: 20px;
}

#container {
    position: relative;
    width: 100vw;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

#points {
    position: relative;
    display: flex;
    width: 250px;
}

#current-points, #high-score {
    position: relative;
    flex: 1;
    text-align: center;
}

#room {
    background-color: black;
}
!

JS 

              
                //Grab the canvas and context
const room = document.querySelector('#room');
const ctx = room.getContext('2d');

//Grab points elements
const curPointsDisplay = document.querySelector('#current-points');
const highScoreDisplay = document.querySelector('#high-score');


//Set initial game variables
const frameRate = 1000 / 15;
const roomWidth = room.width;
const roomHeight = room.height;
const unit = 10;
const roomUnitWidth = room.width / unit;
const roomUnitHeight = room.height / unit;
let curPoints = 0;
let highScore = 0;
let obstacles = [];


//Snake object
let snake = {
    //Props
    "x": 4,
    "y": 4,
    "horDir": 0,
    "vertDir": 0,
    "body": [],
    "bodyLength": 5,
    "canMove": true,

    //Methods
    "travel": (wrapX, wrapY) => {
        //Move snake
        snake.x += snake.horDir;
        snake.y += snake.vertDir;

        //Handle border wrapping
        if (snake.x > wrapX - 1) {
            snake.x = 0;
            snake.canMove = false;
        } else if (snake.x < 0) {
            snake.x = wrapX - 1;
            snake.canMove = false;
        } else if (snake.y > wrapY - 1) {
            snake.y = 0;
            snake.canMove = false;
        } else if (snake.y < 0) {
            snake.y = wrapY - 1;
            snake.canMove = false;
        }
    },

    "checkDeath": (obstacles = []) => {
        //Handle dying
        for (let i = 0; i < snake.body.length; i++) {
            if (snake.horDir + snake.vertDir === 0) { break; } //Break out of loop if snake has yet to move
            if (snake.x === snake.body[i].x && snake.y === snake.body[i].y) {
                return true;
            }
        }

        for (let i = 0; i < obstacles.length; i++) {
            if (snake.x === obstacles[i].x && snake.y === obstacles[i].y) {
                return true;
            }
        }
    },

    "handleBody": () => {
        //Handle body placement
        snake.body.push({ "x": snake.x, "y": snake.y });
        while (snake.body.length > snake.bodyLength) {
            snake.body.shift();
        }
    },

    "eat": () => {
        snake.bodyLength++;
    },

    "reset": () => {
        snake.x = 4;
        snake.y = 4;
        snake.horDir = 0;
        snake.vertDir = 0;
        snake.body = [];
        snake.bodyLength = 5;
    }
};

//Snake controls
function controlSnake(e) {
    let curKey = e.key;
    let direction = snake.horDir + snake.vertDir === 0 ? 'start' : snake.horDir !== 0 ? 'hor' : 'vert'; //Set direction to 'hor' or 'vert' if not first move; otherwise, set it to 'start'

    if (snake.canMove === true) {
        switch (direction) {
            case 'hor':
                if (curKey === 'ArrowUp') {
                    snake.horDir = 0;
                    snake.vertDir = -1;
                    snake.canMove = false;
                } else if (curKey === 'ArrowDown') {
                    snake.horDir = 0;
                    snake.vertDir = 1;
                    snake.canMove = false;
                }
                break;
            case 'vert':
                if (curKey === 'ArrowLeft') {
                    snake.horDir = -1;
                    snake.vertDir = 0;
                    snake.canMove = false;
                } else if (curKey === 'ArrowRight') {
                    snake.horDir = 1;
                    snake.vertDir = 0;
                    snake.canMove = false;
                }
                break;
            case 'start':
                switch (curKey) {
                    case 'ArrowUp':
                        snake.horDir = 0;
                        snake.vertDir = -1;
                        snake.canMove = false;
                        break;
                    case 'ArrowDown':
                        snake.horDir = 0;
                        snake.vertDir = 1;
                        snake.canMove = false;
                        break;
                    case 'ArrowLeft':
                        snake.horDir = -1;
                        snake.vertDir = 0;
                        snake.canMove = false;
                        break;
                    case 'ArrowRight':
                        snake.horDir = 1;
                        snake.vertDir = 0;
                        snake.canMove = false;
                }
        }
    }
}

//Food object
let food = {
    //Props
    "x": 10,
    "y": 10,

    //Methods
    "newPos": (horRange, vertRange, blockedRange, obstacles) => {
        let newX = Math.floor(Math.random() * horRange);
        let newY = Math.floor(Math.random() * vertRange);

        //Block off current food position and all wall positions
        blockedRange.push({ "x": food.x, "y": food.y });
        obstacles.forEach(obj => blockedRange.push(obj));

        for (let i = 0; i < blockedRange.length; i++) {
            if (blockedRange[i].x === newX && blockedRange[i].y === newY) {
                newX = Math.floor(Math.random() * horRange);
                newY = Math.floor(Math.random() * vertRange);
                i = -1;
            }
        }

        food.x = newX;
        food.y = newY;
    },

    "reset": () => {
        food.x = 10;
        food.y = 10;
    }
}

//Wall class
class Wall {
    constructor(x, y) {
        this.x = x;
        this.y = y;
    }
}

//Game
document.addEventListener('DOMContentLoaded', () => {

    //*Essential game functions
    //Handles starting the game
    function startGame() {
        placeObstacles();
        setInterval(runGame, frameRate);
    }

    //Runs the game every frame
    function runGame() {
        //Cycle vars
        let gameOver = false;

        //Runtime progression
        snake.travel(roomUnitWidth, roomUnitHeight); //Move the snake
        snake.canMove = true;

        if (snake.x === food.x && snake.y === food.y) { //Check for snake collision with food; eat food if collision occurs
            food.newPos(roomUnitWidth, roomUnitHeight, snake.body.concat([]), obstacles);
            snake.eat();
            addPoints();
        }

        gameOver = snake.checkDeath(obstacles) ? true : false; //Check if the snake has died and game has ended //!This has to be done before handleBody() to avoid immediate snake death
        snake.handleBody(); //Build the snake body

        //Draw things
        refreshRoom();
        drawRoom();

        //End of cycle checks
        if (gameOver) { restartGame(); }
    }

    //Place obstacles
    function placeObstacles() {
        let positions = [
            [1, 1],
            [1, 2],
            [1, 3],
            [2, 1],
            [3, 1],
            [roomUnitWidth - 2, 1],
            [roomUnitHeight - 3, 1],
            [roomUnitHeight - 4, 1],
            [roomUnitWidth - 2, 2],
            [roomUnitWidth - 2, 3],
            [1, roomUnitHeight - 2],
            [2, roomUnitHeight - 2],
            [3, roomUnitHeight - 2],
            [1, roomUnitHeight - 3],
            [1, roomUnitHeight - 4],
            [roomUnitWidth - 2, roomUnitHeight - 2],
            [roomUnitWidth - 3, roomUnitHeight - 2],
            [roomUnitWidth - 4, roomUnitHeight - 2],
            [roomUnitWidth - 2, roomUnitHeight - 3],
            [roomUnitWidth - 2, roomUnitHeight - 4]
        ];

        for (let i = 0; i < positions.length; i++) {
            let newWall = new Wall(positions[i][0], positions[i][1]);
            obstacles.push(newWall);
        }
    }

    //Adds points
    function addPoints() {
        //Add points
        curPoints++;
        if (curPoints > highScore) { highScore = curPoints; }

        //Display points
        curPointsDisplay.textContent = 'Points: ' + curPoints;
        highScoreDisplay.textContent = 'High score: ' + highScore;
    }

    //Resets the game
    function restartGame() {
        snake.reset();
        food.reset();
        curPoints = 0;
        curPointsDisplay.textContent = 'Points: ' + curPoints;
    }

    //Refreshes the canvas
    function refreshRoom() {
        room.width = roomWidth;
    }

    //Draws all entities
    function drawRoom() {

        //Draw snake head
        ctx.fillStyle = 'white';
        ctx.fillRect(snake.x * unit, snake.y * unit, unit, unit);

        //Draw snake body
        ctx.fillStyle = 'white';
        for (let i = 0; i < snake.body.length; i++) {
            let curX = snake.body[i].x;
            let curY = snake.body[i].y;
            ctx.fillRect(curX * unit, curY * unit, unit, unit);
        }

        //Draw food
        ctx.fillStyle = 'cyan';
        ctx.fillRect(food.x * unit, food.y * unit, unit, unit);

        //Draw obstacles
        ctx.fillStyle = 'gray';
        for (let i = 0; i < obstacles.length; i++) {
            let x = obstacles[i].x;
            let y = obstacles[i].y;
            ctx.fillRect(x * unit, y * unit, unit, unit);
        }
    }

    //Listen for controls
    document.addEventListener('keydown', controlSnake);

    //Initialize game
    startGame();

});
!
999px

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