User:Mr.zessam/sandbox

<!DOCTYPE html> html, body { height: 100%; margin: 0; }

body { background: black; display: flex; align-items: center; justify-content: center; } canvas { border: 1px solid white; }  var canvas = document.getElementById('game'); var context = canvas.getContext('2d');

var grid = 16; var count = 0; var snake = { x: 160, y: 160, // snake velocity. moves one grid length every frame in either the x or y direction dx: grid, dy: 0, // keep track of all grids the snake body occupies cells: [], // length of the snake. grows when eating an apple maxCells: 4 }; var apple = { x: 320, y: 320 };

// get random whole numbers in a specific range // @see https://stackoverflow.com/a/1527820/2124254 function getRandomInt(min, max) { return Math.floor(Math.random * (max - min)) + min; }

// game loop function loop { requestAnimationFrame(loop);

// slow game loop to 15 fps instead of 60 (60/15 = 4) if (++count < 4) { return; }

count = 0; context.clearRect(0,0,canvas.width,canvas.height);

// move snake by it's velocity snake.x += snake.dx; snake.y += snake.dy;

// wrap snake position horizontally on edge of screen if (snake.x < 0) { snake.x = canvas.width - grid; } else if (snake.x >= canvas.width) { snake.x = 0; } // wrap snake position vertically on edge of screen if (snake.y < 0) { snake.y = canvas.height - grid; } else if (snake.y >= canvas.height) { snake.y = 0; }

// keep track of where snake has been. front of the array is always the head snake.cells.unshift({x: snake.x, y: snake.y});

// remove cells as we move away from them if (snake.cells.length > snake.maxCells) { snake.cells.pop; }

// draw apple context.fillStyle = 'red'; context.fillRect(apple.x, apple.y, grid-1, grid-1);

// draw snake one cell at a time context.fillStyle = 'green'; snake.cells.forEach(function(cell, index) {   // drawing 1 px smaller than the grid creates a grid effect in the snake body so you can see how long it is    context.fillRect(cell.x, cell.y, grid-1, grid-1);

// snake ate apple if (cell.x === apple.x && cell.y === apple.y) { snake.maxCells++;

// canvas is 400x400 which is 25x25 grids apple.x = getRandomInt(0, 25) * grid; apple.y = getRandomInt(0, 25) * grid; }

// check collision with all cells after this one (modified bubble sort) for (var i = index + 1; i < snake.cells.length; i++) { // snake occupies same space as a body part. reset game if (cell.x === snake.cells[i].x && cell.y === snake.cells[i].y) { snake.x = 160; snake.y = 160; snake.cells = []; snake.maxCells = 4; snake.dx = grid; snake.dy = 0;

apple.x = getRandomInt(0, 25) * grid; apple.y = getRandomInt(0, 25) * grid; }   }  }); }

// listen to keyboard events to move the snake document.addEventListener('keydown', function(e) { // prevent snake from backtracking on itself by checking that it's   // not already moving on the same axis (pressing left while moving // left won't do anything, and pressing right while moving left // shouldn't let you collide with your own body) // left arrow key  if (e.which === 37 && snake.dx === 0) {    snake.dx = -grid;    snake.dy = 0;  }  // up arrow key  else if (e.which === 38 && snake.dy === 0) {    snake.dy = -grid;    snake.dx = 0;  }  // right arrow key  else if (e.which === 39 && snake.dx === 0) {    snake.dx = grid;    snake.dy = 0;  }  // down arrow key  else if (e.which === 40 && snake.dy === 0) {    snake.dy = grid;    snake.dx = 0;  } });

// start the game requestAnimationFrame(loop);