text: // setup canvas
  
  var canvas = document.querySelector('canvas');
  var ctx = canvas.getContext('2d');
  
  var width = canvas.width = window.innerWidth; //width of the browser viewport
  var height = canvas.height = window.innerHeight; //height of the browser viewport
  
  // define variable for ball count paragraph
  
  var para = document.querySelector('p');
  var count = 0;
  
  // function to generate random number
  
  function random(min,max) {
    var num = Math.floor(Math.random()*(max-min + 1)) + min;
    return num;
  }
  
  //Shape Class
  function Shape(x, y, velX, velY, exists) {
    this.x = x;
    this.y = y;
    this.velX = velX;
    this.velY = velY;
    this.exists = exists;
  }
  
  //Ball constructor, inheriting from Shape
  function Ball(x, y, velX, velY, exists, color, size) {
    Shape.call(this, x, y, velX, velY, exists);
    this.color = color;
    this.size = size;
  }
  
  Ball.prototype = Object.create(Shape.prototype);
  Ball.prototype.constructor = Ball;
  
  
  //DRAWING THE BALL
  Ball.prototype.draw = function() {
    ctx.beginPath(); //state that we want to draw a shape on the canvas
    ctx.fillStyle = this.color; //color the drawn shape
    ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
    //The this.x and this.y is the position of the arc's center
    //The this.size -->The radius of our arc
    //The 0 and 2*Math.PI --> specify the start and end number of degrees round the circle that the arc is drawn between. 1*PI will only result to 180degrees
    ctx.fill(); //states "finish drawing the path we started with beginPath()
  }
  
  // var testBall = new Ball(50, 100, 4, 4, 'blue', 10);
  
  
  //UPDATING THE BALL'S DATA
  Ball.prototype.update = function() {
  //the ball is going off the right hand edge
    if ((this.x + this.size) >= width) { 
      this.velX = -(this.velX);
    }
  //the ball is going off the left hand edge
    if ((this.x - this.size) <= 0) {
      this.velX = -(this.velX);
    }
  //the ball is going off the bottom edge
    if ((this.y + this.size) >= height) {
      this.velY = -(this.velY);
    }
  //the ball is going off the top edge
    if ((this.y - this.size) <= 0) {
      this.velY = -(this.velY);
    }
  
    this.x += this.velX;
    this.y += this.velY;
  }
  
  //BALL COLLISION DETECTION
  Ball.prototype.collisionDetect = function() {
    for(var j = 0; j < balls.length; j++) {
      if(!(this === balls[j])) {
        var dx = this.x - balls[j].x;
        var dy = this.y - balls[j].y;
        var distance = Math.sqrt(dx * dx + dy * dy);
  
        if (distance < this.size + balls[j].size && balls[j].exists) {
          balls[j].color = this.color = 'rgb(' + random(0,255) + ',' + random(0,255) + ',' + random(0,255) +')';
        }
      }
    }
  }
  
  //EvilCircle constructor inheriting from shape
  function EvilCircle(x, y, exists) {
    Shape.call(this, x, y, 20, 20, exists);
    this.color = 'white';
    this.size = 10;
  }
  
  EvilCircle.prototype = Object.create(Shape.prototype);
  EvilCircle.prototype.constructor = EvilCircle;
  
  //EvilCircle draw method
  EvilCircle.prototype.draw = function() {
    ctx.beginPath();
    ctx.strokeStyle = this.color;
    ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
    ctx.stroke();
  }
  
  //EvilCircle checkBounds method
  
  EvilCircle.prototype.checkBounds = function() {
    if((this.x + this.size) >= width) {
      this.x -= this.size;
    }
  
    if((this.x - this.size) <= 0) {
      this.x += this.size;
    }
  
    if((this.y + this.size) >= height) {
      this.y -= this.size;
    }
  
    if((this.y - this.size) <= 0) {
      this.y += this.size;
    }
  }
  
  // define EvilCircle setControls method
  
  EvilCircle.prototype.setControls = function() {
    var _this = this;
    window.onkeydown = function(e) {
      if(e.keyCode === 65) { // a
        _this.x -= _this.velX;
      } else if(e.keyCode === 68) { // d
        _this.x += _this.velX;
      } else if(e.keyCode === 87) { // w
        _this.y -= _this.velY;
      } else if(e.keyCode === 83) { // s
        _this.y += _this.velY;
      }
    }
  }
  
  // define EvilCircle collision detection
  
  EvilCircle.prototype.collisionDetect = function() {
    for(var j = 0; j < balls.length; j++) {
      if( balls[j].exists ) {
        var dx = this.x - balls[j].x;
        var dy = this.y - balls[j].y;
        var distance = Math.sqrt(dx * dx + dy * dy);
  
        if (distance < this.size + balls[j].size) {
          balls[j].exists = false;
          count--;
          para.textContent = 'Ball count: ' + count;
        }
      }
    }
  }
  
  
  
  //ANIMATING THE BALL
  var balls = [];
  
  // define loop that keeps drawing the scene constantly
  var evil = new EvilCircle(random(0,width), random(0,height), true);
  evil.setControls();
  
  function loop() {
    ctx.fillStyle = 'rgba(0, 0, 0, 0.25)';
    ctx.fillRect(0, 0, width, height);
  
    while (balls.length < 25) {
      var size = random(10,20);
      var ball = new Ball(
        // ball position always drawn at least one ball width
        // away from the edge of the canvas, to avoid drawing errors
        random(0 + size,width - size),
        random(0 + size,height - size),
        random(-7,7),
        random(-7,7),
        true,
        'rgb(' + random(0,255) + ',' + random(0,255) + ',' + random(0,255) +')',
        size
      );
      balls.push(ball);
      count++;
      para.textContent = 'Ball count: ' + count;
    }
  
    for (var i = 0; i < balls.length; i++) {
      if(balls[i].exists) {
        balls[i].draw();
        balls[i].update();
        balls[i].collisionDetect();
      }
    }
  
    evil.draw();
    evil.checkBounds();
    evil.collisionDetect();
  
    requestAnimationFrame(loop);
  }
  
  
  
  loop();
  
  