let x = 0;

let speedY = 3;

let y = 0;

​

function setup() {  

   createCanvas(400, 400);

}

​

function draw() {  

   background(0);  

   stroke(255);  

   strokeWeight(4);  

   noFill();  

   ellipse(x, y, 20, 20); 

  //Checking canvas edges

  if(x>width || x<0){

    speedX = -speedX;

  }

  if(y>height || y<0){

    speedY = -speedY;

  }

  x = x + speedX;

  y = y + speedY; 

}

​