script.js

let canvas = document.getElementById("snake");
let context = canvas.getContext("2d");
let box = 32; /*tamanho dos quadradinhos */
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 = "#DCDCDC";
    context.fillRect(0, 0, 16 * box, 16 * box);
}

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

function drawFood(){
    context.fillStyle = "red"; /*cor do alimento */
    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);
            alert('game over :(');
        }
    }

    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;
    }

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

    snake.unshift(newHead);}

let Jogo = setInterval(iniciarJogo, 100);