snakegame/snakegame.html at master · simranbhatt/snakegame · GitHub

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<!--  Hi! It's nice to see you here. :) If you have questions or suggestions,
      please email me at simrankbhatt@gmail.com. Happy snaking!

      Modifications:
      Snake resizes itself to 4 after reaching a length of 50
      Added a reset button (R on the keyboard)
      Added a score and high score display
       snake now bounces back from the left & right walls and ceiling of the canvas rather than passing through to the other side.
       Canvas size is larger
      -->

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

  body {
    background: black;
    display: flex;
    align-items: center;
    justify-content: center;
  }
  canvas {
    border: 10px solid white;
  }
  </style>

 </head>

 <body>
  <canvas width="800" height="600" id="game"></canvas>

  <script>
var canvas = document.getElementById('game');
var context = canvas.getContext('2d');


var grid = 16;
var count = 0;

//snake object

var snake = {
  x: 80,
  y: 80,

  // 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: [],
  score: 0,
  highScore: 0,

  // length of the snake. grows when eating an apple
  maxCells: 4
};

var apple = {
  x: 320,
  y: 320
};

//function to produce a random integer within a given range
function getRandomInteger(min, max) {
  return Math.floor(Math.random() * (max - min)) + min;

}

function loop() {
   requestAnimationFrame(loop);

   //speed of snake. 60/15 = 4
   if(++count < 4) {
      return;
   }

   count = 0;

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

   //moving the snake by its defined velocity (see snake object)
   snake.x += snake.dx;
   snake.y += snake.dy;


    //keeping the snake within canvas boundaries
   if(snake.x <= 0) {
     snake.x = 0;
     snake.dx = grid;
     snake.dy = 0;
    } else if(snake.x >= canvas.width) {
        snake.x = canvas.width;
        snake.dx = -grid;
        snake.dy = 0;
    }

    if(snake.y <= 0) {
      snake.y = 0;
      snake.dy = 16;
      snake.dx = 0;
    } else if(snake.y >= canvas.height) {
      snake.y = 0;
      snake.dy = 16;
      snake.dx = 0;
    }

     //adding the current coordinate of the snake to the array keeping track of snake length
    snake.cells.unshift({x: snake.x, y: snake.y});

   //make sure the snake length is as defined
   if(snake.cells.length > snake.maxCells) {
    snake.cells.pop();
    }

    //score count
    context.fillStyle = 'yellow';
    context.font = "20px Georgia";
    context.fillText("Score: ", 15, 30);
    context.font = "23px Georgia";
    context.fillText(snake.score, 75, 30);

    //high score count
    context.font = "14px Serif";
    context.fillText("High Score: ", 15, 55);
    context.font = "15px Serif";
    context.fillText(snake.highScore, 85, 55);

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

    //draw snake
    context.fillStyle = 'green';
    //fill each coordinate stored in the cells array (in the snake object) with green
    snake.cells.forEach(function(cell, index) {

        context.fillRect(cell.x, cell.y, grid-1, grid-1);

       //increase snake length when it 'eats' the apple
        if(cell.x == apple.x && cell.y == apple.y) {
            snake.maxCells++;
            snake.score++;

            if(snake.score > snake.highScore) {
                 snake.highScore = snake.score;
            }
             //canvas size is 800x600 = 75x25 grids?
            apple.x = getRandomInteger(0, 50) * grid;
            apple.y = getRandomInteger(0, 25) * grid;

         }
     }); //close forEach (snake drawing function)

    //reset snake size when it reaches a size of 50. This prevents the snake from taking up most of the screen and affecting the gameplay
    if(snake.maxCells >= 50) {
        snake.x = 160;
        snake.y = 160;
        snake.cells = [];
        snake.maxCells = 4;
        snake.dx = grid;
        snake.dy = 0;

      } //close if statement
  } //close game loop

// 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)

  //reset button (press R on the keyboard to reset the game)
  if(e.which == 82) {
       snake.x = 160;
        snake.y = 160;
        snake.cells = [];
        snake.maxCells = 4;
        snake.dx = grid;
        snake.dy = 0;
        snake.score = 0;
        apple.x = getRandomInt(0, 25) * grid;
        apple.y = getRandomInt(0, 25) * grid;
  }
  // 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> <!-- javascript ends -->

</body>
</html>