script.js

let canvas = document.getElementById("snake");
let context = canvas.getContext("2d");
let placar = document.getElementById("placar");
let pontos = 0;
let box = 32;
let fim = document.querySelector(".gameover");
let restart = document.querySelector(".btn");
restart.addEventListener("click",function(){
    location.reload();
})
let snake = [];
snake[0] = {
    x: 8 * box,
    y: 8 * box
}
let direction = "right";
let food = {
    x: Math.floor(Math.random() * 15 + 1) * box,
    y: Math.floor(Math.random() * 15 + 1) * box
}

function criarBG(){
    context.fillStyle = "lightgreen";
    context.fillRect(0, 0, 16 * box, 16 * box);
}

function criarCobrinha(){
    for(i=0; i<snake.length; i++){
        context.fillStyle = "green";
        context.fillRect(snake[i].x, snake[i].y, box, box);
    }
}

function drawFood(){
    context.fillStyle = "red";
    context.fillRect(food.x, food.y, box, box);
}

document.addEventListener("keydown", update);

function update(event){
    if(event.keyCode == 37 && direction != "right")
        direction = "left";
    if(event.keyCode == 38 && direction != "down")
        direction = "up";
    if(event.keyCode == 39 && direction != "left")
        direction = "right";
    if(event.keyCode == 40 && direction != "up")
        direction = "down";
}

function iniciarJogo(){
    if(snake[0].x > 15 * box && direction == "right")
        snake[0].x = 0;
    if(snake[0].x < 0 && direction == "left")
        snake[0].x = 16 * box;
    if(snake[0].y > 15 * box && direction == "down")
        snake[0].y = 0;
    if(snake[0].y < 0 && direction == "up")
        snake[0].y = 16 * box;

    for(i=1; i<snake.length; i++){
        if(snake[0].x == snake[i].x && snake[0].y == snake[i].y){
            clearInterval(jogo);
            fim.classList.add('ativo');
        }
    }

    criarBG();
    criarCobrinha();
    drawFood();

    let snakeX = snake[0].x; 
    let snakeY = snake[0].y;

    if(direction == "right") snakeX += box;
    if(direction == "left") snakeX -= box;
    if(direction == "up") snakeY -= box;
    if(direction == "down") snakeY += box;

    if(snakeX != food.x || snakeY != food.y){
        snake.pop();
    }else{
        food.x = Math.floor(Math.random() * 15 + 1) * box,
        food.y = Math.floor(Math.random() * 15 + 1) * box
        pontos++;
        placar.innerText= pontos;
    }


    let newHead = {
        x: snakeX,
        y: snakeY
    }

    snake.unshift(newHead);

}

let jogo = setInterval(iniciarJogo, 100);