crazzyguti/README.md

## README.md

      
    Raw
  

              README.md
            
          
    Basic Snake HTML Game

Snake is a fun game to make as it doesn't require a lot of code (less than 100 lines with all comments removed). This is a basic implementation of the snake game, but it's missing a few things intentionally and they're left as further exploration for the reader.
Further Exploration


Score

When the snake eats an apple, the score should increase by one. Use context.fillText() to display the score to the screen


Mobile and touchscreen support

Allow the game to be scalled down to a phone size. See https://codepen.io/straker/pen/VazMaL
Support touch controls


Better apple spawning

Currently the apple spawns in any random grid in the game, even if the snake is already on that spot. Improve it so it only spanws in empty grid locations


License

(CC0 1.0 Universal) You're free to use this game and code in any project, personal or commercial. There's no need to ask permission before using these. Giving attribution is not required, but appreciated.

  
## snake.html
<!DOCTYPE html>
<html>
<head>
  <title></title>
  <style>
  html, body {
    height: 100%;
    margin: 0;
  }

  body {
    background: black;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  canvas {
    border: 1px solid white;
  }
  </style>
</head>
<body>
<canvas width="400" height="400" id="game"></canvas>
<script>
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);
</script>
</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<title></title>
	<style>
	html, body {
	height: 100%;
	margin: 0;
	}

	body {
	background: black;
	display: flex;
	align-items: center;
	justify-content: center;
	}
	canvas {
	border: 1px solid white;
	}
	</style>
	</head>
	<body>
	<canvas width="400" height="400" id="game"></canvas>
	<script>
	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);
	</script>
	</body>
	</html>